uratinr 


;  BERKELEY 
.IBRARY 
NIVERSITY  OF 
CALIFC" 


v 


.UNIVERSITY 


DISTRIBUTION    AND    ORIGIN 
OF   LIFE    IN    AMERICA 


DISTRIBUTION  AND 

ORIGIN  OF  LIFE  IN 

AMERICA 


BY 

ROBERT  FRANCIS  SCHARFF 

Ph.D.,  B.Sc. 

Author  of  "European  Animals,  their  Geological  History  and  Geographical  Distribution. 

Corresponding  Member  of  the  Academy  of  Natural  Sciences,  Philadelphia; 

of  the  Senckeriberg  Natural  History  Society,  Frankfurt  a] Main  ; 

of  the  Linnean  Society  of  Bordeaux ;  and  of  the 

Anthropological  Society  of  Paris 


NEW   YORK 

THE    MACMILLAN    COMPANY 

1912 


QU5 

: 


-PALI& 

LIBRARY 


EARTH 

SCIENCES 

LtBRARY 


PREFACE 

THIS  volume  is  the  outcome  of  the  second  series  of  "  Swiney 
Lectures  "  on  Geology  which  I  delivered  at  the  Victoria  and 
Albert  Museum  in  London  in  1908.  The  subject  chosen  for 
these  lectures  was  the  "  Geological  History  of  the  American 
Fauna."  Instead  of  publishing  the  lectures,  like  the  previous 
ones  on  the  "  European  Fauna,"  with  little  alteration,  I  decided 
to  amplify  and  rewrite  them  completely.  In  doing  so  I  was 
enabled  to  bring  out  more  clearly  certain  points  in  the 
geological  history  of  the  American  animals  which  seemed 
to  me  of  general  interest. 

It  is  always  difficult  to  choose  a  suitable  title  for  a  work  of 
this  kind.  The  one  I  have  selected  is  brief  yet  comprehen- 
sive. At  the  same  time,  it  may  be  urged  that  the  origin  and 
distribution  of  Man  might  reasonably  be  expected  from  the 
title,  whereas  it  has  been  omitted  in  the  text.  This  omission 
is  mainly  due  to  the  fact  that  the  literature  dealing  with  the 
subject,  exclusive  of  Man,  is  very  extensive,  while  the  origin 
and  distribution  of  human  races  in  America  is  treated  in  quite 
a  distinct  set  of  periodicals  and  books. 

An  important  feature  of  my  researches  is  the  elucidation  of 
some  of  the  problems  connected  with  the  cause  and  nature  of 
the  "  Ice  Age  "  or  "  Glacial  Epoch."  There  is  a  considerable 
amount  of  faunistic  evidence  that  both  the  Atlantic  and  the 
Pacific  oceans  were  closed  simultaneously  in  the  north,  result- 
ing in  a  higher  temperature  of  these  oceans  and  a  greater 
snowfall  in  the  countries  surrounding  them  in  the  north. 
Similarly,  if  the  Glacial  Epoch  had  been  due  to  a  closing  of  the 
Arctic  Ocean,  the  higher  temperature  prevailing  in  the  Arctic 

247501 


vi  PEEFACE 

area  during  early  Tertiary  times  must  have  been  caused  by  a 
more  abundant  supply  of  warm  currents  in  the  Arctic  Ocean 
at  that  time.  Consequently  North  America  would  probably 
have  been  more  isolated  in  the  north  than  it  is  now,  for  the 
currents  must  have  had  ample  facilities  for  passing  freely  into 
the  Arctic  Ocean.  Palaeontological  evidence,  however,  points 
to  an  intimate  union  of  North  America  and  the  Old  World 
during  the  greater  part  of  the  Tertiary  Era.  There  are  thus  a 
number  of  interesting  problems,  all  of  which  are  fully  dis- 
cussed in  this  volume,  quite  apart  from  many  other  important 
theories  arising  out  of  the  subject  of  the  origin  and  distribution 
of  life  in  North  America.  In  this  connection  the  testimony 
of  fossil  animals,  and  that  of  the  marine  fauna,  has  been  largely 
availed  of.  To  a  certain  degree  the  distribution  of  plants  has 
also  been  included. 

I  have  endeavoured,  as  far  as  possible,  to  quote  all  the  more 
noteworthy  works  and  papers  dealing  with  the  subject  under 
consideration.  Nevertheless  I  am  conscious  of  having  possibly 
overlooked  a  few  important  contributions ;  and  I  only  hope  my 
colleagues  will  be  good  enough  to  draw  my  attention  to  any  omis- 
sions that  they  may  notice,  so  as  to  enable  me  to  add  them  in 
case  a  second  edition  of  this  book  should  be  called  for.  I  can 
lay  no  claim  to  having  made  careful  studies  of  the  literature 
dealing  with  the  Geology  or  Botany  of  the  American  continents. 
The  works  cited  are  those  that  I  happened  to  be  acquainted 
with,  and  no  doubt  many  gaps  might  be  filled  by  those  more 
conversant  with  these  sciences  than  I  am. 

I  have  hesitated  for  some  time  before  actually  illustrating 
my  views  as  to  the  former  changes  of  land  and  water.  Some 
geologists  consider  it  inadvisable  to  publish  palaeogeographical 
maps  founded  on  zoogeographical  data,  since  such  maps  are 
very  liable  to  revision  according  to  the  constantly  advancing 
state  of  our  knowledge.  The  latter  are  also  apt  to  lead  to  a 
good  deal  of  adverse  criticism,  for  one  map  can  only  represent 
a  single  short  phase  of  a  long  series  of  geological  ages  during 
which  repeated  changes  of  land  and  water  probably  took 
place.  In  spite  of  these  objections  I  have  ventured  to  con- 
struct a  few  of  these  ideal  maps  of  ancient  geography  as  a 


PREFACE  vii 

general  illustration  of  my  views.  I  have  felt  that  although  I 
am  open  to  criticism,  my  views  will  be  more  easily  understood, 
and  we  shall  eventually  make  more  rapid  progress  in  arriving 
at  the  correct  conclusions  as  to  the  alterations  in  the  configura- 
tion of  the  oceans  and  continents  that  actually  occurred  in 
the  past  than  if  such  maps  were  altogether  omitted. 

The  immense  advance  that  has  been  made  in  the  United 
States  in  the  study  of  zoology  has  greatly  facilitated  my  work. 
And  everywhere  in  America  I  found  willing  helpers  ready  to 
impart  information.  My  thanks  are  particularly  due  in  this 
respect  to  Prof.  H.  F.  Osborn,  Dr.  Matthew  and  Dr.  Hornaday 
of  New  York,  to  Prof.  Morse  and  Mr.  John  Kitchie  of  Boston, 
to  Dr.  Henry  B.  Bigelow  and  Mr.  T.  Barbour  of  Harvard 
University,  to  the  late  Dr.  A.  E.  Brown  and  Mr.  Witmer  Stone 
of  Philadelphia,  to  Dr.  Dall,  Dr.  T.  W.  Vaughan,  Dr.  Stejneger 
and  Miss  Kichardson  of  Washington,  to  the  late  Prof.  Packard 
of  Providence,  to  Dr.  Ortmann  of  Pittsburg,  to  Dr.  Van  Den- 
burgh  of  San  Francisco  and  to  Dr.  Kuthven  of  Ann  Arbor. 
Several  of  my  European  friends  also  aided  me  in  many  ways. 
Among  them  particularly  the  following  members  of  the  staff 
of  the  British  Museum  :  Dr.  Smith  Woodward,  who  was  good 
enough  to  look  through  the  proofs  and  to  draw  my  attention 
to  several  errors,  Dr.  Andrews,  Dr.  Boulenger,  Mr.  Eegan, 
Mr.  Pycraft  and  Mr.  B.  B.  Woodward.  Prof.  Hull,  Dr.  Bruce 
and  Dr.  Stapf  kindly  pointed  out  to  me  various  valuable 
sources  of  information.  My  most  grateful  acknowledgment, 
moreover,  is  due  to  the  guardians  of  the  Great  Libraries,  with- 
out whose  ready  assistance  I  should  never  have  succeeded  in 
accomplishing  this  work.  The  most  generous  facilities  for 
study  were  given  me  by  my  friends  Mr.  Lyster  of  the 
National  Library  of  Ireland,  Mr.  Praeger  of  the  Koyal  Irish 
Academy  Library  and  Dr.  Foord  of  the  Royal  Dublin  Society's 
Library.  I  am  indebted,  too,  for  many  services  to  Mr.  Kappel, 
the  Librarian  of  the  Linnean  Society,  to  Mr.  Jones,  Librarian 
of  the  Geological  Society,  Mr.  Waterhouse  of  the  Zoological 
Society  of  London,  and  Mr.  Hinch  of  the  National  Library  of 
Ireland. 

I  am  under  a  great  obligation  to  Messrs.  Meiklejohn  &  Son 


viii  PREFACE 

for  allowing  me  to  reproduce  two  of  their  beautiful  oroscopic 
maps,  while  the  council  of  the  Eoyal  Irish  Academy,  Prof. 
Osborn,  Dr.  von  Ihering,  Dr.  Ortmann,  Mr.  Thompson  Seton, 
Dr.  True  and  Dr.  Hornaday  were  good  enough  to  give  me 
permission  to  copy  maps  illustrating  their  works. 

I  can  scarcely  hope  that  all  the  conclusions  I  have  arrived 
at  in  this  book  will  be  readily  accepted,  but  I  trust  to  have 
succeeded  in  impressing  those  who  have  not  made  a  serious 
study  of  the  science  of  geographical  distribution  of  animals 
with  the  profound  importance  of  the  subject  as  an  aid  to 
palaeogeographical  researches. 

B.  F.  S. 

TUDOR  HOUSE, 

DUNDRUM,  Co.  DUBLIN, 

November  11th   1911. 


CONTENTS 

CHAPTEE  I 

THE  FAUNA  OF  GREENLAND 

PAGE 

Description  of  Greenland — The  reindeer  and  its  origin — The 
Arctic  musk  ox — The  lemming  and  Arctic  hare — On  the 
ancient  land  connections  between  Greenland  and  the  adjoining 
continents — On  the  cause  of  the  Ice  Age — The  marine  fauna  of 
the  North  Atlantic  cited  as  evidence  in  favour  of  a  northern 
land  connection — Did  the  fauna  of  Greenland  survive  the  Ice 
Age  in  the  country  ? — The  snails  of  Greenland  quoted  in  support 
of  this  theory — On  the  supposed  polar  origin  of  life — General 
faunistic  affinities  of  Greenland  with  other  northern  countries  .  1-25 

CHAPTER   II 

THE  FAUNA  OF  NORTH-EASTERN  NORTH  AMERICA 

Description  of  the  general  features  of  Labrador  and  its  fauna — The 
voles  and  jumping  mice — On  some  northern  frogs — The  origin 
and  distribution  of  the  moose  deer — The  fauna  of  the  White 
Mountains  and  its  origin — Pre- Glacial  relict  colonies  in  the 
North-East — Supposed  effect  of  the  Ice  Age  on  the  fauna — 
Were  the  animals  driven  south  by  the  cold  ? — On  mild  inter- 
glacial  phases  of  the  Glacial  Epoch — Foraminifera  in  the  Glacial 
drift  deposits — The  relict  fauna  of  the  Great  Lakes — The 
fishes  of  the  Great  Lakes  and  their  origin — Distribution  and 
geological  history  of  the  fresh-water  mussel  Margaritana — The 
past  history  of  the  Great  Lakes — The  fauna  of  Newfoundland  26-57 

CHAPTEE  III 

THE  ANIMALS   OF  THE  CANADIAN  NORTH-WEST 

The  Mackenzie  basin  and  its  fauna — The  lemmings  and  gophers 
— On  American  ptarmigans — The  past  history  of  the  bison  and 
its  gradual  destruction — On  the  distribution  and  origin  of 
the  wapiti  deer — The  Canadian  tree  -  porcupine — On  the 
molluscan  fauna  of  the  north-west  and  its  relationship  .  58-73 


x  CONTENTS 

CHAPTER  IV 

THE  FAUNA  OF  ALASKA 

PAGE 

On  the  general  features  of  Alaska,  its  glaciers,  volcanoes  and  flora- 
Conditions  of  Alaska  during  the  Glacial  Epoch— On  the  evidences 
derived  from  the  fossil  mammals  as  to  the  former  climate  of 
the  country — Evidences  of  an  Asiatic  invasion  of  animals  into 
Alaska— The  faunistic  affinities  of  Alaska— On  the  former 
presence  of  the  mammoth  in  Alaska — The  fresh-water  fishes  of 
Alaska— The  distribution  and  origin  of  the  butterflies  belonging 
to  the  genus  Parnassius — On  the  mammals  peculiar  to  Alaska — 
On  the  relationship  of  the  marine  mollusks  of  the  northern 
Pacific  in  recent  and  past  times— Evidences  of  a  former  land 
bridge  near  Bering  Strait 74-100 

CHAPTER  V 

THE  ROCKY  MOUNTAINS  AND  THEIR  INHABITANTS 

The  region  of  the  Great  Salt  Lake— Distribution  and  origin  of  the 
jnountain  sheep  and  Rocky  Mountain  goat — On  the  geological 
history  of  the  American  deer  tribe — the  prong-horn  antelope 
and  its  origin — On  the  Eocky  Mountain  flora — Accidental 
distribution  as  applied  to  butterflies  —  Description  of  the 
American  game  preserves — The  great  Tertiary  deposits  and 
their  contents  .  .  101-122 


CHAPTER  VI 

THE  ANIMALS   OF  THE  EASTERN  STATES 

On  the  poverty  of  lizards  in  this  region — The  snakes  of  the  eastern 
states  and  their  affinities — The  origin_and  distribution  of  the 
garter  snakes — Rattlesnakes  and  their  range — On  American 
tortoises  and  turtles — The  giant  salamanders  of  America  and 
Asia — On  newts  and  their  allies — The  relationship  of  the 
Eastern  plants — The  pine-barren  flora — The  range  of  the 
star-nosed  mole 123-143 

CHAPTER  VH 

THE  FAUNA  OF  THE  CONTINENTAL  BASIN 

Description  of  the  prairie  region  and  its  inhabitants — On  the  extinc- 
tion of  the  horse  in  America  and  the  geological  history  of  the 
horse  tribe — Prairie  dogs  and  their  distribution — On  the  origin 
and  past  history  of  the  raccoon — On  caves  and  their  contents  as 
illustrating  the  geological  history  of  the  fauna — The  former 


CONTENTS  xi 


presence  of  the  reindeer  south  of  its  existing  range — Evidences 
of  a  southern  fauna  in  the  north  and  of  its  gradual  southward 
retreat — Helicina — Turkeys  and  the  Florida  parrot — On  the 
dispersal  of  fresh- water  mussels — Eelicts  of  the  past — Bony-pike 
and  bow-fin — The  blind  fauna  of  America .  144-166 


CHAPTER  VIII 

THE   SOUTH-EASTERN   STATES  AND   BERMUDA 

On  the  vegetation  and  general  features  of  Florida — The  geological 
history  of  Florida — On  the  reptiles  and  amphibians  of  the  south- 
east— The  south-east  as  a  centre  of  dispersal — The  terrestrial 
mollusks  of  Florida — On  scorpions  and  dragon-flies — Alligators 
and  crocodiles,  their  origin  and  past  history — The  fauna  of 
Bermuda  island — The  geology  and  flora  of  Bermuda — The  birds 
and  their  origin — Terrestrial  isopods,  spiders  and  the  land 
nemertean  worm  Geonemertes — On  the  snails  of  Bermuda  and 
their  ancestors — The  origin  of  the  Bermudan  fauna  .  167-195 

CHAPTEE  IX 

SOUTH-WESTERN  NORTH    AMERICA  AND   ITS  FAUNA 

On  the  so-called  "  Sonoran  Region  " — The  palaeogeography  of 
California  and  the  adjoining  States — On  the  western  insecti- 
vores — On  horned  toads  and  burrowing  lizards — Discontinuous 
distribution  of  some  western  toads — The  snails  of  California — 
The  fauna  of  lower  California  and  its  Cape  region — On  the 
European  element  of  the  Calif ornian  fauna  as  illustrated  by  the 
mollusks,  butterflies  and  ants — The  crayfishes  of  the  south- 
west and  their  origin — Various  faunistic  problems — On  mam- 
malian affinities — The  American  rabbits  and  their  relations — 
The  former  Atlantic  land  connections  between  the  New  World 
and  the  Old,  supported  by  the  evidence  derived  from  Tertiary 
mammals — Conclusions 196-232 

CHAPTER   X 

THE  FAUNA  OF  CENTRAL  AMERICA 

The  fishes  of  Central  America  and  their  origin — On  the  geology  and 
palaeogeography  of  Central  America — Importance  of  deter- 
mining the  age  of  Central  America — Evidence  derived  from  a 
study  of  the  marine  faunas — On  the  faunistic  affinities  between 
North  and  South  America — The  flora  of  Central  America — 
Monkeys  and  raccoons — On  birds,  tortoises  and  snakes — The 


xii  CONTENTS 

PACK 

fresh- water  crabs  and  their  dispersal — The  European  element  in 
the  fauna  of  Central  America — -Oil  discontinuous  distribution 
of  animals  as  a  proof  of  their  antiquity  ....  233-260 


CHAPTER  XI 

THE  WEST  INDIAN  ISLANDS  AND  THEIR  INHABITANTS 

The  geology  of  the  Antilles — Palaeography  as  illustrated  by  the  dis- 
tribution of  snails — Antiquity  and  dispersal  of  snails,  their 
relationship  and  European  affinities — On  the  theory  of  the 
ancient  Atlantis — The  problem  of  the  supposed  permanence  of 
ocean  basins — The  marine  mammals  of  the  Antilles  and  their 
origin — Evidences  in  favour  of  a  mid- Atlantic  land  bridge — 
The  terrestrial  mammals  of  the  West  Indian  islands — Evidences 
of  former  changes  of  level  in  the  Antillean  area — The  blind 
animals  of  Cuba — On  the  ancient  Antillean  continent  261-294 


CHAPTER  XII 

THE  FAUNA  AND   FLORA  OF  THE   GALAPAGOS  ISLANDS 

Darwin's  visit  to  the  islands  and  his  views  on  the  origin  of  their 
animals  and  plants — On  accidental  dispersal — The  birds, 
tortoises  and  snails  of  the  Galapagos  islands — Origin  of  the 
flora — Baur's  criticisms  of  Darwin's  views — Euphorbia  and 
its  past  history — Conclusions  as  to  the  origin  of  the  Galapagos 
fauna — The  geological  history  of  the  Pacific  Ocean — On  the 
supposed  former  Pacific  continent — Mr.  Guppy's  researches- 
Coral  reefs  and  their  history — A  circum-Pacific  land  belt — 
Evidences  of  ancient  lands  westward  of  Central  America — On 
faunistic  affinities  between  the  Atlantic  and  Pacific  oceans — 
The  Humboldt  current  .  295-335 


CHAPTER  XIII 

THE  ANIMALS   OF   THE   NORTH-WESTERN   STATES   OF  SOUTH  AMERICA 

The  geological  history  of  South  America — The  faunal  elements  of 
the  continent — Palaeontology — Course  of  development  of  the 
continent  during  the  Tertiary  Era — Peripatus  and  its  distribu- 
tion in  South  America — On  the  origin  of  Clausilia  and  its 
relations — The  South  American  bear — On  the  tapirs  and  their 
origin — The  dwarf  deer  of  South  America — On  the  supposed 
existence  of  former  land  connections — Derivation  and  history 
of  the  fossil  elephants — The  river  Amazon  .  .  .  336-362 


CONTENTS  xiii 

CHAPTER  XIV 

THE  FAUNA  OF  EASTERN   SOUTH  AMERICA 

PAGK 

South  American  monkeys,  their  distribution  and  geological  history 
— Sloths — The  birds  of  South  America — On  fossil  mammals  and 
Old  World  affinities — The  theory  of  an  ancient  land  connection 
between  South  America  and  Africa — Evidence  derived  from 
the  distribution  of  reptiles,  amphibians,  fishes,  mollusks  and 
fresh- water  crabs — Dr.  von  Ihering's  researches — Fernando  de 
Noronha  and  St.  Helena — The  fauna  of  St.  Helena  and  its 
antiquity — Tristan  da  Cunha 363-394 

CHAPTER  XV 

ARGENTINA  AND  CHILE 

The  fauna  of  Argentina — Prof.  Ameghino's  discoveries  of  fossils 
and  their  importance — Fossil  edentates  and  rodents — Faunistic 
affinities — The  llama  and  its  origin — Fossil  elephants — Ancient 
land  connections  between  South  and  North  America — Fossil 
plants  —  Floral  affinities  —  The  oircum-Pacific  land  belt — 
Antarctic  problems — On  the  Antarctic  continent — Affinities 
of  the  faunas  of  Patagonia  and  New  Zealand — On  a  Pacific 
continent — The  marine  fauna  of  Patagonia — The  Falkland 
islands— Antarctic  expeditions — The  pendulation  theory  395-435 


LIST    OF   ILLUSTRATIONS 


1.  Map  of  North  America  (reproduced  from  Meiklejohn's  oro- 

scopic  maps  by  permission  of  Messrs.  Meiklejohn  &  Son)       .         1 

2.  Map  of  the  North  Atlantic,  showing  the  supposed  conditions 

of  land  and  water  during  later  Pliocene  times  (reproduced  by 
permission  of  the  Council  of  the  Eoyal  Irish  Academy)  .  16 

3.  Map  of  North  America,  showing  the  distribution  of  the  Moose 

Deer  (reproduced  by  permission  of  Mr.  Thompson  Seton)      .       32 

4.  Map  showing  the  outlines  of  the  White  Mountain  Plateau  and 

Mount  Washington,  with  an  inset  Map  of  North  America 
indicating  the  geographical  position  of  the  White  Mountains  36 

5.  Map  of  North  America  showing  the  original  distribution  of  the 

Bison,  the  range  of  the  same  species  after  the  completion  of 
the  Union  Pacific  Railroad  and  its  present  range  (reproduced 
by  permission  of  Dr.  Hornaday) 65 

6.  Map  of  North  America,  showing  the  original  distribution  of  the 

Wapiti  deer,  and  its  range  in  1900  (reproduced  by  permission 

of  Mr.  Thompson  Seton)          .......      67 

7.  Map    of    the    northern    parts  of    the    northern    hemisphere, 

showing  the  supposed  land  connections  and  the  extent  of  the 

sea  in  the  early  part  of  the  Glacial  Epoch      ....      98 

8.  Map  of  the  World,  indicating  the    distribution  of  the  newt 

Spelerpes 138 

9.  Map  of  North  America,  showing  the  distribution  of  the  Star- 

nosed  Mole  (reproduced  by  permission  of  Dr.  True)       .        .142 

10.  Map  of  North  America,  showing  the  distribution  of  the  Bein- 

deer  (reproduced  with  some  modifications  by  permission  of 
Mr.  Thompson  Seton) 155 

11.  Map  of  North  and  South  America,  showing  the  distribution  of 

the  snail  Helicina 158 

12.  Map  of  the  World,  showing  the  distribution  of  the  family  of 

fishes  Cichlidae  (reproduced  by  permission  of  Mr.  Tate  Eegan)    234 


xvi  LIST   OF   ILLUSTKATIONS 

FIG.  FAQ 

13.  Map  of  the  West  Indian  Area,  showing  the  position  of   the 

principal  islands      .........     262 

14.  Map  of  North  and    South  America,   indicating  roughly  the 

supposed  conditions  of  land  and  water  about  the  commence- 
ment of  the  Tertiary  Era        .         .         ...         .         .280 

15.  Map  of  the  World,  showing  the  conditions  of  land  and  water 

in  upper  Cretaceous  times  according  to  Dr.  Ortmann  (repro- 
duced with  the  author's  permission)       .         ...         .         .     292 

16.  Map  of  North  and  South  America,  indicating  roughly    the 

supposed  conditions  of  land  and  water  about  the  middle  of 

the  Tertiary  Era      .         .         .         .         ...       .,,      .294 

17.  Map  of  the  World,  showing  the  conditions  of  land  and  water 

during  the  Eocene  Period,  according  to   Dr.  von   Ihering 
(reproduced  with  the  author's  permission)      .       ,.        .         .314 

18.  Map  of  South  America  (reproduced  fromMeiklejohn'soroscopic 

maps,  by  permission  of  Messrs.  Meiklejohn  &  Son)         .         .     336 

19.  Map  indicating  the  distribution  of  the  snail  Clausilia  in  the 

Mediterranean  region,  in  Africa  and  America,  with  an  inset 
figure  of  Clausilia  (Nenia)       .......     349 

20.  Map  of  the  World,  showing  the  conditions  of  land  and  water 

in  lower  Tertiary  times,  according  to  Dr.   Ortmann  (repro- 
duced with  the  author's  permission)       .         .         ....     382 

21.  Map  of  the  World,  showing  the  conditions  of  land  and  water 

in   late  Cretaceous   and  basal  Eocene  times,  according  to 
Professor  Osborn  (reproduced  with  the  author's  permission)     419 


Highland  over  1,000  Feet. 
Upland  under  1.000  Feet. 
Lowland  under  600  Feet. 


. — Map  of  North  America.     (Reproduced  from  Meiklejohn's  Oroscopic 
Map,  by  permission  of  Messrs.  Meiklejohn  &  Son.) 


[To  face  p.  1, 


Distribution  and   Origin 
of  Life  in  America 


CHAPTER  I 

THE    FAUNA   OF    GREENLAND 

GREENLAND  geographically  belongs  to  arctic  America 
rather  than  to  Europe,  and,  as  it  no  doubt  formed  part  of  the 
land  bridge  that  once  connected  America  and  Europe,  its  past 
history  contains  chapters  of  the  greatest  interest.  Scanty 
as  the  fauna  and  flora  of  Greenland  are,  they  afford  us  many 
a  clue  as  to  former  changes  of  land  and  water  which  th&t 
country  has  undergone.  Their  study  enables  us  also  to  trace 
the  origin  of  the  animals  and  plants  of  the  neighbouring  por- 
tion of  continental  America,  which  is  one  of  the  objects  of 
the  present  work. 

Greenland  is  now  too  well  known  to  need  a  long  description. 
Yet  few  readers  realise  the  vast  size  of  this  stern  and 
uninviting  country,  which  covers  an  area  considerably  larger 
than  the  whole  of  France  and  Germany  together.  Three- 
quarters,  at  least,  of  this  area  being  completely  buried 
under  an  enormous  glacier  ice-sheet,  or  inland  ice,  only  a 
comparatively  narrow  belt  of  partly  barren  rocky  ground  is 
left  along  the  shore  on  which  animal  and  plant  life  is  possible. 
The  broadest  exposed  strip  of  land  on  the  west  coast  of  Green- 
land is  about  a  hundred  miles  .wide.  Here  and  ther e  two 
kinds  of  willows  and  the  dwarf  birch  together  form  scrubby 
low- growing  woods,  the  stems  rarely  rising  more  than  a  few 
feet  from  the  ground.  Thickets  of  alder,  white  birch  and 
dwarf  juniper  likewise  occur,  while  in  sheltered  nooks  the 

L.A.  B 


2  OK  JOIN.  OF   LIFE   IN   AMERICA 

Lapland  rhododendron,  many  kinds  of  saxifrages,  cinquefoil, 
crowfoot,  a  willow-herb,  a  lousewort,  the  narrow-leaved  arnica 
and  other  flowering  plants  for  a  time  infuse  variety  into  the 
brownish-grey  landscape,  giving  it  quite  a  gay  appearance 
with  the  many  brightly-coloured  blossoms.  During  a  couple 
of  weeks  in  the  short  summer  the  natives  may  even  have  the 
advantage  of  gathering  crow-berries  (Empetrum  nigrum), 
which  grow  in  great  abundance  almost  everywhere,  just  as 
they  do  in  boreal  America  and  Europe.  "The  bilberry  and 
cowberry  are  also  noticeable,  but  they  are  less  common  and 
do  not  seem  to  be  used  by  the  natives,  nor  is  the  cloudberry, 
whose  fruit  rarely  ripens.  All  these  are  well-known  American 
and  European  plants.  The  most  valuable  vegetable,  which  is 
largely  used  for  food,  is  a  tall  angelica.  It  sometimes  attains 
a  height  of  six  feet  in  favourable  localities. 

During  early  Tertiary  times  many  species  of  conifers  and 
several  of  our  common  deciduous  oaks,  poplars,  walnuts, 
maples,  lindens,  magnolias  and  beeches  flourished  in  Green- 
land. Many  of  the  same  trees  also  lived  in  Iceland,  Spits- 
bergen, Grinnell  Land,  boreal  North  America  and  the  New 
Siberian  islands.  It  is  evident  that  the  climate  all  round 
the  Arctic  Ocean  must  have  been  mild.  Many  causes  have 
been  assigned  for  the  change  from  the  former  temperate 
climatic  conditions  to  the  arctic  ones  now  prevailing  in  the 
eame  region.  A  less  restricted  circulation  of  warm  ocean 
water  into  the  circumpolar  area  might,  as  has  been  suggested, 
help  to  bring  about  such  a  state.  Yet  it  would  not  alone  be 
sufficient.  Sun  and  light  for  a  longer  period  than  now  obtains 
would  seem  to  have  been  necessary  to  ripen  the  wood  of  the 
trees  and  bring  the  fruit  to  maturity.  At  any  rate,  all  this 
luxuriant  flora  must  have  disappeared  from  these  northern 
regions  long  before  the  Ice  Age.  It  is  quite  possible,  and  I 
even  think  it  probable,  that  many  of  our  common  arctic  and 
alpine  plants  originated  in  these  remote  Tertiary  times.  I 
cannot  adduce  any  direct  geological  evidence  for  such  a  belief, 
since  few  of  these  plants  possess  properties  which  would 
enable  the  remains  of  their  leaves  to  be  preserved  in  a  fossil 
condition.  The  assumption  is  founded  chiefly  on  their  wide 
geographical  distribution. 

As   I   am  dealing   mainly   with   faunistic   problems,    the 


REINDEER   AND   ITS   ORIGIN  3 

animals  of  Greenland  have  to  be  considered  more  in  detail.  It 
is  especially  the  beasts  or  mammals  that  are  of  importance 
because  their  distribution  and  geological  history  are  better 
known  than  those  of  the  smaller  animals.  They  also  enable 
us  to  readily  appreciate  the  more  recent  changes  in  the  fauna, 
and  the  causes  which  have  led  to  them. 

The  most  noteworthy  and  best  known  of  the  Greenland 
mammals  is  the  reindeer.  The  term  reindeer  (Eangifer 
tarandus)  is  employed  for  the  sake  of  convenience  in  its  wide 
sense.  In  America  it  has  been  the  custom  for  many  years 
past  to  distinguish  under  the  names  of  "  barren-ground 
caribou,"  and  "  woodland  caribou  "  two  strikingly  different 
forms  which  occur  on  the  continent,  the  term  "  caribou  " 
being  probably  derived  from  the  Indian  word  "  maccaribo." 
Not  only  have  these  two  kinds  of  'reindeer  dissimilar  habits, 
they  also  differ  from  one  another  in  size,  and  in  the  structure 
of  their  skulls  and  antlers.  More  recently,  smaller  groups  of 
reindeer  have  been  discovered,  showing  distinctive  characters 
in  their  antlers  alone.  Several  of  the  nine  forms  thus 
recognised  as  American  are  founded  upon  comparatively 
slight  differences.  An  illustrated  account  of  these  various 
American  reindeer  has  been  given  by  Mr.  Madison  Grant.* 

Mr.  Lydekker  f  holds  that  they  and  the  Old  World  forms 
are  all  referable  to  one  single  species,  of  which  he  distin- 
guishes six  varieties.  Whether  these  differences  are  to  be 
regarded  as  specific  or  varietal  is  a  matter  of  opinion,  but, 
as  th,e  antlers  of  reindeer  are  so  very  variable,  it  has  been 
suggested  by  Professor  Camerano  that  the  structure  of  the 
skull  might  be  utilised  to  greater  advantage  in  discriminating 
between  the  various  varieties  or  species.  In  his  researches 
on  the  Spitsbergen  form,  he  argues  that  there  are  three 
species,  viz.,  the  reindeer  of  Spitsbergen  (R.  spitsbergensis). 
the  one  inhabiting  Greenland,  Norway,  Lapland  and  part  of 
Siberia  (R.  tarandus),  and  lastly  the  American  reindeer  (R. 
caribou) .  Among  the  last  two  species  he  distinguishes  again 
between  the  reindeer  possessing  cylindrical  (cylindricornis) 
and  those  having  compressed  (compressicornis)  antlers. 

It  is  worthy  of  note  that  the  reindeer  of  Scandinavia  and 

*  Grant,  Madison,  "  The  Caribou." 

f  Lydekker,  E.,  "  The  Deer  of  all  Lands,"  p.  33. 

B  2 


4  OBIGIN   OF   LIFE   IN   AMERICA 

Greenland  constitute  a  single  variety,  according  to  Professor 
Camerano,*  while  Mr.  Lydekker  separates  the  Scandinavian 
from  the  Greenland  race.  Following  Professor  Camerano's 
example,  Dr.  Lonnberg  f  prefers  the  nasal  bones  of  the  skull, 
to  the  antlers  for  specific  diagnosis.  He  unites  the  Greenland, 
Spitsbergen  and  Scandinavian  forms  with  the  American 
barren-ground  reindeer  in  one  group,  characterised  by  their 
flat  nasals.  ^The  Finland  and  Siberian  reindeer  he  holds  to 
be  quite  distinct  races,  particularly  the  former,  which,  with 
its  elevated  nasal  bones  and  somewhat  flattened  antlers,  ap- 
proaches the  American  woodland  caribou.  Even  Robert 
Brown  J  long  ago  commented  on  the  likeness  of  the  Green- 
land and  European  reindeer,  remarking  that  some  reindeer 
horns  from  Greenland  could  not  be  distinguished  from 
European  ones.  Since  Professors  Camerano  and  Lonnberg, 
moreover,  take  both  skull  characters  and  antlers  into  con- 
sideration, we  may  assume  that  this  view  of  the  affinity  of  the 
Greenland  to  the  north-west  European  race  is  likely  to  be  the 
correct  one. 

An  anonymous  writer  in  "  Natural  Science,"  (p.  358, 
1899)  gave  it  as  his  opinion  that  there  are  no  grounds  for 
deciding  whether  the  Old  or  the  New  World  was  the  original 
home  of  the  reindeer.  No  doubt  he  meant  to  convey  that  we 
know  nothing  of  the  ancestry  of  the  reindeer.  I  ventured,  § 
on  the  contrary,  to  put  forward  the  theory  that  the  reindeer 
had  originated  in  the  Polar  area,  beyond  the  confines  of  the 
European  Continent,  while  Professor  Schlosser  ||  argued  that 
it  was  evidently  of  American  origin.  Neither  of  these  views 
is  supported  by  positive  geological  evidence ;  nevertheless 
I  cannot  agree  with  the  above  critic  that  we  possess  no  grounds 
for  deciding  the  place  of  origin  of  the  reindeer,  as  the  results 
of  Professor  Camerano's  and  Professor  Lonnberg's  cranial 
researches  seem  to  indicate  the  existence  of  a  closer  rela- 
tionship between  the  west  European  and  the  Greenland  and 

*  Camerano,  L.,  "  Renne  delle  Isole  Spitzberge,"  p.  167. 
t  Lonnberg,  Einar,  "  Taxonomic  Notes  about  Reindeer,"  p.  10. 
|  Brown,  Robert,  "Mammals  of  Greenland,"  p.  352. 
§  Scharff,  R.  F.,  "  History  of  European  Fauna,"  p.  155. 
||   Schlosser,  M.,M  Beziehungen  d.  ausgestorben.     Siiugethier-faunen," 
p.  617. 


REINDEEK   AND   ITS   ORIGIN  5 

arctic  American  varieties  than  between  the  west  European 
and  the  Siberian  reindeer.  The  assumption  that  the  species 
originated  in  Greenland  or  arctic  America  and  thence  spread 
along  old  land  connections  east  and  west  to  Europe  arid  Asia, 
is,  therefore,  not  quite  so  unjustified  ias  Dr.  Stejneger  *  seems 
to  think. 

But  we  must  not  forget  the  possibility  of  the  reindeer 
having  originated  in  the  Old  World.  Dr.  Brown  f  argues 
that  the  barren-ground  variety  spread  to  America  from 
western  Europe  by  way  of  a  Spitsbergen-Greenland  land 
connection,  while  the  other  traversed  Siberia,  and  crossed  to 
the  New  World  by  Bering  Strait.  In  the  more  southern 
parts  of  its  range  in  America,  new  varieties  may  have 
arisen,  perhaps  owing  to  changes  in  the  natural  sur- 
roundings. Long  cylindrical  antlers  were  no  doubt  a  dis- 
advantage to  reindeer  in  wooded  districts,  hence  the  beam 
became  reduced  in  length  and  increased  in  width  in  what  is 
known  in  America  as  the  "  woodland  caribou."  Some  of  these 
varieties,  or  species  as  many  American  naturalists  choose  to 
call  them,  intergrade  to  such  an  extent  as  to-be  difficult  to  dis- 
criminate from  one  another.  Thus  Rangifer  stonei  is  a  form 
of  barren-ground  reindeer  living  in  Alaska,  while  Rangifer 
osborni  is  a  woodland  form.  Dr.  Allen,  who  first  described 
them,  considers  them  as  well-marked  species,  while  Mr. 
Osgood,J  during  his  travels  in  Alaska,  finds  that  the  differ- 
ences between  the  two  are  all  relative,  that  they  are  excessively 
variable  and  rather  intangible.  The  mountain  caribou  (Ran- 
gifer montanus),  originally  described  by  Mr.  Thompson 
Seton,  is  considered  by  Dr.  Allen  §  to  be  allied  to  the  wood- 
land form,  but  distinguished  from  it  in  colour,  size  and  shape 
of  antlers.  Mr.  Seton, ||  who  has  published  a  most  instructive 
map  of  the  geographical  distribution  of  the  caribou  in  North 
America,  which  has  furnished  me  with  the  materials  for  the 
map  given  in  this  work  (Fig.  10),  thinks  that  in  future  the 

*  Stejneger,    L.,    "  ScharfE's     History    of     the     European    Fauna," 
p.  112. 

f  Brown,  A.  E.,  "  North  American  Big  Game,"  p.  87. 
J   Osgood,  W.  H.,  "  North  American  Fauna,"  33,  p.  17. 
§  Allen,  J.  A.,  "Mountain  Caribou,"  pp.  8  &  9. 
||    Seton,  E,  Thompson,  "Northern  Animals,  I.,"  p.  192, 


6  OKIGIN   OF   LIFE   IN   AMERICA 

ten  species  now  recognised  in  America  will  be  reduced  to 
four  well-marked  species. 

How  long  the  caribou  or  reindeer  has  been  in  existence 
we  do  not  know.  Its  remains  have  been  discovered  both  in 
Europe  and  America  in  deposits  believed  to  have  been  laid 
down  during  the  Pleistocene  Period,  and  as  these  occur  far 
to  the  south  of  its  present  range,  it  has  invariably  "been 
assumed  that  the  species  was  compelled,  owing  to  unfavour- 
able climatic  changes  to  abandon  its  more  northerly  habitat. 
When  the  climate  became  once  more  suitable  to  its  require- 
ments, the  reindeer  is  supposed  to  have  returned  to  its,  original 
home.  This  idea  suggests  that  the  reindeer  originated  in 
pre-Glacial  times,  and  this  view  is,  in  my  opinion,  supported 
by  the  evidence  of  its  occurrence,  conjointly  with  the  hyaena, 
in  Irish  cave  deposits.* 

The  whole  subject  of  the  influence  of  the  Glacial  Epoch 
on  animals  and  plants  will  be  dealt  with  later  on,  and  need 
not  be  considered  here.  The  fact  of  the  occurrence  of  un- 
doubted reindeer  remains  far  to  the  south  of  its  present 
range  certainly  requires  an  explanation,  and  this  is  more 
easily  given  in  conjunction  with  other  facts  to  be  stated 
in  this  chapter.  While  .the  reindeer  still  lives  in  Europe  no 
/further  south  than  the  fifty-second  degree  of  latitude,  in 
America  it  is  found  no  less  than  seven  degrees  further  south. 
In  former  times  it  inhabited  Oregon  and  Kentucky.  In  the 
east  it  came  down  to  the  neighbourhood  of  the  present  site 
of  New  York  City,  whereas  in  Europe  it  advanced  as  far  as 
Mentone  on  the  shores  of  the  Mediterranean,  and  penetrated 
to  the  north  of  Spain,  i.e.,  to  the  latitudes  of  the  thirty-eighth 
degree  in  America  and  of  the  forty-third  degree  in  Europe.f 

The  musk  ox  (Ovibos  moschatus)  is  another  even  more 
arctic  mammal  than  the  reindeer.  So  called  from  the  musky 
odour  of  its  flesh,  this  species  was  believed  to  be  more  closely 
allied  to  the  sheep  than  to  the  ox,  which  it  resembles  more  in 
gize.  In  its  geographical  distribution  it  differs  strikingly 
from  that  of  the  reindeer  in  so  far  as  it  is  now  quite  confined 
to  Greenland  and  arctic  North  America.  It  no  longer  inhabits 

*  Scharff,  R  F.,  "  European  Animals,"  p.  112. 
t  Brauer,  A.,  "  Die  arktische  Subregion." 


AECTIC   MUSK  OX  7 

the  Old  World.  Yet  in  Europe  it  penetrated  as  far  as  England 
and  France  in  Pleistocene  times,  having  apparently  reached 
these  countries  from  an  eastward  direction.  While  the  rein- 
deer occurs  even  in  southern  Greenland,  the  musk  ox 
frequents  only  the  north  and  east  of  that  country. 

According  to  Dr.  Conwentz,  it  has  only  wandered  east- 
ward from  the  north  coast  of  Greenland  in  recent  times. 
At  any  rate,  Professor  Nathorst  alleges  that  Scoresby,  in  the 
year  1822,  did  not  observe  it  in  the  neighbourhood  of  the 
Sound  which  bears  his  name,  though  it  is  now  found  there. 
Nevertheless,  the  discovery  of  some  very  ancient  skulls 
between  the  seventieth  and  seventy-fifth  degrees  of  latitude 
on  the  same  coast  make  it  probable  that  the  musk  ox  lived 
in  that  region  in  more  remo'te  times,  afterwards  becoming 
extinct  only  to  advance  once  more  to  its  former  habitat  in: 
recent  times.* 

The  musk  ox  to  most  observers  has  appeared  to  be  subject  to 
little  variation.  Mr.  Lydekker,  however,  described  a  form 
from  eastern  Greenland  (Ovibos  moschatus  wardi)  with  a 
whitish  face-patch  and  lighter  general  colouration,  which 
Dr.  Allen  f  has  since  raised  to  specific  rank,  showing  that  it 
also  differed  from  the  type  in  the  structure  of  the  horns  and 
hoofs.  The  latter  likewise  pointed  out  that  it  was  not  con- 
fined to  Greenland,  but  inhabited  also  Ellesmere  and  Grinnell 
Land. 

Another  form  of  musk  ox,  an  almost  black  one,  from  the 
far  north  of  Canada,  was  first  noticed  and  described  by  Mr. 
Elliot.  A  renewed  examination  of  musk  ox  skins  and  skulls 
was  recently  undertaken  by  Dr.  KowarzikJ  with  rather  re- 
markable results.  He  recognises  two  strikingly  distinct 
groups  of  "musk  oxen,  a  western  and  an  eastern  group, 
characterised  by  very  important  osteological  and  external 
features,  which  had  apparently  escaped  the  attention  of  pre- 
vious observers.  In  a  private  letter  he  admitted  to  me 
that  the  musk  ox  must  have  originated  in  North  America, 
Bootherium  being  probably  its  direct  ancestor.  Yet  he  is 
evidently  inclined  to  believe  that,  after  spreading  by  way  of 

*  Conwentz,  "  Yerbreitung  d.  Moschusochsen,"  pp.  429 — 431. 
t  Allen,  J.  A.,  "  Musk-Oxen  of  Arctic  America,"  p.  76. 
I  Kowarzik,  E.,  "  Der  Moschusochs,"  p.  120. 


8  OKIGIN  OF   LIFE   IN  AMERICA 

Asia  to  Europe,  it  became  extinct  in  America  as  well  as  in 
Greenland. 

Part  of  one  section  of  the  old  musk  ox  stock  returned  to 
North  America  by  way  of  Asia,  while  another  travelled  by 
means  of  a  north  Atlantic  land  connection  to  southern  Green- 
land, gradually  finding  its  way  along  the  eastern  and  western 
coasts  to  northern  Greenland.  Meanwhile  the  musk  ox  had 
entered  Alaska  again  from  Asia  and  crossed  the  Mackenzie 
Eiver  into  arctic  Canada,  where  some  of  the  peculiar  forms 
originated. 

Dr.  Kowarzik  promises  us  further  contributions  to  this 
interesting  problem  from  a  palaeontological  point  of  view. 
These  will  be  of  particular  value  in  elucidating  the  question 
of  the  relationship  between  the  European  and  the  Greenland 
forms  of  the  musk  ox.  I  agree  in  so  far  with  Dr.  Kowarzik, 
as  I  feel  convinced  that  the  musk  ox  originated  in  North 
America  in  pre-Glacial  times,  but  I  differ  in  most  of  his  other 
views.  If  land  connections  existed  between  North  America 
and  Asia,  and  between  North  America  and  Europe,  they  must 
have  persisted  through  Pliocene  to  early  Pleistocene  times. 
I  am  of  opinion,  therefore,  that  the  musk  ox  spread  east- 
ward to  Europe  and  westward  to  Asia  as  long  as  land 
bridges  enabled  it  to  do  so.  It  is  quite  possible  that  the 
Asiatic  section  subsequently  travelled  westward  to  Europe, 
but  neither  of  them  succeeded  in  returning  to  their  native 
lajid.  The  musk  oxen  we  find  in  Greenland  and  arctic 
America  probably  survived  the  Ice  Age.  where  they  now 
live.  This  opinion  has  the  support  of  Dr.  F.  Wright  *  and 
Professor  Upham  as  the  result  of  their  special  study  of  the 
geological  history  of  Greenland. 

Not  long  ago  the  musk  ox  was  still  found  in  Alaska.  Now 
it  has  been  quite  exterminated  west  of  the  Mackenzie  Kiver. 
As  Dr.  Allen  remarks,  the  genus  Ovibos  is  a  declining  type, 
which  has  attained  its  last  stronghold  in  the  arctic  barren 
grounds.  Wherever  it  is  within  the  grasp  of  man  it  will 
soon  be  a  creature  of  the  past. 

We  possess  no  undoubted  evidence  of  the  existing  species 
of  musk  ox  having  ever  penetrated  as  far  south  as  the  United 
Sta;tes,  nevertheless  it  is  quite  possible  that  the  fragmentary 

*  Wright,  F.  F.,  and  Warren  Upham,  "  Greenland  Icefields,"  p.  332. 


LEMMING   AND   AKCTIC   HAKE  9 

remains  which  have  been  discovered  in  caves  and  other  super- 
ficial (Pleistocene)  deposits  in  Pennsylvania,  Kentucky,  Mis- 
souri, Iowa  and  Ohio  may  have  belonged  to  varieties  of  Ovibos 
moschatus  rather  than  to  extinct  species  of  musk  oxen. 

There  are  two  other  arctic  mammals  which  are  of  special 
interest  to  us,  since  both  of  them  inhabit  Greenland.  They 
are  the  arctic  hare  (Lepus  variabilis  =  L.  timidus)  and  the  arctic 
lemming  (Dicrostonyx  torqnatus  =  Cuniculus  torquatus). 

Like  the  reindeer,  the  arctic  hare  is  subject  to  great  varia- 
tion over  the  vast  area  which  it  inhabits,  and  some  of  these 
varieties  or  races  are  now  recognised  by  many  zoologists  as 
species.     Mr.  R.  Brown  *  long  ago  felt  the  difficulty,  nay, 
almost  impossibility,  in  discriminating  between  the  Green- 
land hare  and  the  arctic  or  varying  hare  of  Europe.    The  same 
embarrassment  has  confronted  many  subsequent  authors.   In 
American-he  Greenland  hare  is  now  generally  considered  as 
specifically   distinct   from   the   arctic  American    hare,    Mr. 
Rhoads  f  having  pointed  out  some  important  features  in  its 
incisor  teeth,  while  Mr.  Nelson  J  finds  that  its  excessively 
heavy  wool -like  coat  of  fur,  the  long  claws  and  tapering  upper 
mandible  sufficiently  distinguish  it  from  its  relatives  on  the 
American  Continent  to  give  it  the  rank  of  separate  species. 
However,  as  Mr.  Rhoads  aptly  remarks  (p.  356)  the  peculiar 
dentition,  long  fur,  and  long  claws  are  due  partly  to  the 
scantiness  and  character  of  plant  life,  and  partly  to  the  depth 
and  long  continuance  of  the  snow  in  Greenland.    These  fea- 
tures seem  to  have  gradually  impressed  themselves  on  the 
Greenland  hare  in  modifying  it  in  the  direction  indicated. 
In  Major  Barrett-Hamilton's  §  opinion  the  chief  differences 
between  the  European  arctic  hares  and  the  Greenland  form, 
from  an  external  point  of  view,  are  only  of  a  su|b- specific 
value,  while  Dr.  Winge  ||  does  not  specifically  distinguish  the 
American  or  European  arctic  hares  from  the  Greenland  one. 
The  same  problem  of  affinity  has  recently  been  investigated 
from  a  new  standpoint  by  Mr.  Hinton.   His  researches  have 

*  Brown,  R.,  "  Mammals  of  Greenland,"  p.  351. 

t  Rhoads,  S.  N.,  u  Polar  Hares  of  North  America,"  p.  368. 

|  Nelson,  E.  W.,  "  Rabbits  of  North  America,"  p.  68. 

§  Barrett-Hamilton,  G.  E.  H.,  "  The  Variable  Hare,"  p.  92. 

||  Winge,  H.,  "  Gronlands  Pattedyr,"  p.  376. 


10  ORIGIN   OF   LIFE   IN   AMERICA 

led  him  to  a  comparison  of  the  fossil  hare  remains  from  the 
ossiferous  fissures  of  Ightham  in  England  with  the  recent 
polar  or  arctic  hares  as  a  whole.  He  has  been  exceptionally 
fortunate  in  disposing  of  large  osteological  collections,  and 
his  conclusions  are  of  particular  interest  and  of  much  value 
in  elucidating  some  important  zoogeographioal  problems. 
Dwelling  upon  the  close  affinity  existing  between  the  English 
fossil  and  the  Irish  living  arctic  hare,  he  regards  the  latter 
as  the  direct  descendant  of  the  former.  I  should  not  have 
mentioned  these  particulars  except  that  they  give  rise  to  far- 
reaching  deductions.  From  the  fact  of  the  fossil  English  and 
recent  Irish  forms  being  the  least  specialized  members  of  the 
whole  group  of  arctic  hares,  Mr.  Hinton  concludes  that  it  is 
highly  improbable  that  the  group  can  have  had  a  boreal 
origin.* 

That  the  Irish  arctic  hare  has  always  lived  in  Ireland  under 
temperate  conditions  is  an  opinion  which  I  expressed  long 
ago  in  my  works  on  the  European  fauna,  and  in  this  view  Mr. 
Hinton  concurs.  But  I  also  believe,  as  I  shall  endeavour 
to  demonstrate  later  on,  that  even  southern  Greenland  and 
all  the  lands  surrounding  the  north  Atlantic  had  a  milder 
climate  during  the  Pleistocene  Period.  It  is  principally  the 
climate  of  arctic  America  and  Greenland,  I  think,  that  be- 
came much  more  unfavourable  within  recent  geological  times, 
while  that  of  the  British  Isles  has  undergone  comparatively 
little  alteration.  Meanwhile  specialization  among  the  animals 
constituting  the  Greenland  fauna  probably  proceeded  at  a 
more  rapid  rate  than  in  Ireland,  where  the  hare  had  no  need 
to  become  adapted  to  different 'conditions  of  food 'and  tempera- 
ture. In  spite  of  Mr.  Hinton 's -argument,  I  still  believe  in  the 
arctic  origin  of  the  group  in  Pliocene  times,  mainly  because  I 
do  not  admit  that  we  have  any  evidence  for  the  assumption 
that  Ireland  was  connected  with  Great  Britain  during  or 
after  the  Pleistocene  Period.  Mr.  Hinton  thus  differs  from 
me  in  regarding  Central  Asia  as  the  centre  of  origin  of  the 
arctic  hares  in  Pleistocene  times. 

I  mentioned  that  the  banded  lemming  (Dicrostonyx  tor- 
quatus)  was  found  in  Greenland.  Of  late  years  it  has  been 

*  Hinton,  M.  A.  C.,  "  The  fossil  hare  of  Ightham,"  pp.  263—264. 


ANCIENT   LAND   CONNECTIONS  11 

customary  to  distinguish  the  New  World  form  (D.  hud- 
sonius)  from  the  Old  World  banded  lemming  (D.  torquatus), 
but  they  are  very  closely  allied.  Several  varieties  of  the 
former  inhabit  the  mainland  and  islands  of  arctic  America, 
including  the  north  and  east  coasts  of  Greenland.  The 
whole  genus  Dicrostonyx  (Myodes),  is  confined  to  the  Arctic 
Eegions.  As  in  the  case  of  the  reindeer  and  other  arctic 
species,  we  possess  fossil  testimony  of  a  former  southern 
extension  of  the  range  of  the  banded  lemming  in  Europe.* 
It  occurred  in  Central  Europe,  and  also  in  England  and 
Ireland,  yet,  as  far  as  we  know,  it  never  penetrated  into  the 
United  States  in  Pleistocene  times.  That  the  banded  lemming 
is  not  a  recent  immigrant  to  Greenland,  but  has  persisted 
there  from  pre-Glacial  times  seems  to  be  indicated  by  the 
fact  that  Colonel  Feilden  f  discovered  its  remains,  with  those 
of  the  reindeer  and  musk-ox,  in  post-Tertiary  (Pleistocene) 
deposits  from  sea-level  to  an  altitude  .of  1,000  feet  in  northern 
Greenland. 

There  are  a  couple  of  other  mammals  in  Greenland,  viz : 
the  arctic  wolf  and  the  arctic  fox,  which  need  not  be  specially 
considered  here.  Nevertheless,  a  significant  factor  in  connec- 
tion with  one  of  these  carnivores  has  been  pointed  out  by 
Major  Barrett-Hamilton  and  Mr.  Bonhote.J  It  is  that  the 
arctic  fox  (Vulpes  lagopus)  of  Spitsbergen,  Novaya  Zemlya 
and  Iceland  agrees  with  that  from  eastern  Greenland,  form- 
ing a  variety  distinct  from  those  of  the  European  and 
American  mainlands. 

All  the  mammals  alluded  to  as  inhabiting  Greenland,  live 
also  in  Europe  in  identical  or  closely  allied  forms,  or  did  so  in 
former  times.  Hence  it  is  permissible  to  argue  that  a  land- 
connection  once  bridged  over  the  intervening  ocean.  The 
affinity  between  Greenland  and  arctic  America  in  some 
respects  is  even  closer  than  that  between  Greenland  and 
Europe.  Only  the  narrow  Davis  Strait  and  the  still  narrower 
Kennedy  Channel  separate  the  two  countries.  Another 

*  Scharff,  E.  F.,  G.  Coffey,  and  others,  "  Caves  of  Kesh,"  p.  196. 

t  Feilden,  H.  W.,  and  C.  E.  de  Eance,  "Geology  of  Arctic  Coasts," 
p.  566. 

t  Barrett-Hamilton,  G.  E.  H.,  and  I.  L.  Bonhote,  "  Sub-species  of 
Arctic  Fox,"  p.  288. 


12  ORIGIN   OF   LIFE   IN   AMERICA 

sound  of  inconsiderable  width,  Bering  Strait,  divides  arctic 
America  from  the  Asiatic  Continent.  We  can  easily  imagine 
what  a  comparatively  small  change  in  the  configuration  of 
land  and  water  would  thus  bring  Greenland  into  direct  touch 
with  Asia,  by  way  of  arctic  America  (compare  Fig.  1). 

It  has  actually  been  suggested  by  several  writers  that  the 
faunal  relationship  which  exists  between  Greenland  and 
Europe  is  due  to  former  land  bridges  across  Bering  Strait 
and  Davis  Strait,  facilitating  the  passages  of  animals  from 
Europe  by  way  of  Asia.  That  such  land  connections  really 
existed  in  recent  geological  times,  I  do  not  doubt,  and  they 
will  be  further  described  in  this  and  one  of  my  next  chapters. 
Still,  their  existence  does  not  preclude  the  possibility  of 
Greenland  having  likewise  been  connected  by  land  directly 
with  Europe.  A  close  relationship  exists  between  some  of  the 
western  European  and  Greenland  mammals.  In  some  in- 
stances that  affinity  is  no  longer  apparent  in  the  recent 
mammalian  fauna,  but  can  be  demonstrated  to  have  once  been 
a  prominent  feature.  The  extinct  Irish  reindeer  for  example, 
clearly  indicates,  in  the  character  of  its  skull  and  antlers, 
that  it  was  closely  related  to  the  present  Greenland  and  arctic 
American  races  of  reindeer,  thus  suggesting  the  former 
existence  of  some  more  direct  means  of  transit  from  Green- 
land to  Ireland,  or  vice  versa,  than  by  the  circuitous  route 
across  Europe,  Asia  and  arctic  America.  Many  authorities, 
indeed,  have  on  other  grounds  insisted  upon  the  former 
presence  of  a  land  bridge  uniting  Scotland,  the  Faroes, 
Iceland  and  Greenland,  with  America. 

The  story  of  the  extermination  of  the  indigenous  reindeer 
in  Iceland  in  the  twelfth  century  is  too  vague  to  be  of  much 
use  in  connection  with  these  researches.  It  appears  certain, 
at  any  rate,  that  no  reindeer  had  inhabited  Iceland  for  some 
hundreds  of  years  before  the  end  of  the  eighteenth  century, 
when  the  ancestors  of  the  present  stock  were  brought  over 
from  Finmark.  The  assumption  of  the  existence  of  such 
a  land  connection  as  that  referred  to,  in  Pliocene,  and  perhaps 
early  Pleistocene  times,  or,  in  other  words,  just  before  and 
during  the  beginning  of  the  Glacial  Epoch,  is  generally  based 
upon  other  ground  than  the  distribution  of  mammals.  I  have 
recently  collected  the  various  sources  of  evidence  in  favour 


GREENLAND-EUROPE   LAND  BRIDGE  13 

of    the    theory    from    the    oceanographical,    geological    and 
biological  standpoints.* 

A  second  land  bridge  apparently  united  northern  Greenland 
and  Lapland  at  about  the  same  time.  This  I  described  on  a 
previous  occasion.  It  will  not  be  necessary  for  me  to  repeat 
all  the  arguments  I  advanced  for  and  against  the  hypothesis, 
and  I  must  content  myself  with  a  short  statement  of  the  main 
facts.  The  theory  of  the  Greenland-Iceland- Scotland  land 
bridge  (Fig.  2)  had  been  put  forward  by  quite  a  number  of 
authorities  on  independent  grounds.  Yet  while  some  maintain 
that  it  merely  existed  in  early  Tertiary  times,  others  contend 
that  it  could  .only have  been  made  use  of  by  the  .members  of  our 
present  fauna  and  flora  after  the  Glacial  Epoch,  because  the 
latter  had  not  yet  come  into  existence  before  that  time. 

One  of  the  most  important  facts  in  favour  of  the  existence  of 
this  land  bridge  is  presented,  in  my  opinion,  by  the  geographi- 
cal distribution  of  the  land  snail  known  as  Helix  hortensis. 
I  have  quoted  many  other  instances  in  my  paper  on  this 
subject,  but  this  no  doubt  affords  the  most  striking  biological 
support  for  the  belief  in  a  land  connection  between  Scotland, 
Iceland,  Greenland  and  Labrador. 

Helix  hortensis  is  a  typically  west  European  species,  being 
quite  unknown  in  the  eastern  parts  of  Europe  or  in  Asia. 
Beyond  the  mainland  of  Europe  we  find  it  in  Great  Britain, 
in  Ireland,  the  Shetland  Islands,  the  Faroes,  Iceland,  in 
southern  Greenland,  Labrador,  the  islands  off  the  north-east 
coast  of  North  America,  and  part  of  the  opposite  mainland. 

Biologists  are  often  too  ready  in  invoking  human  agency 
when  endeavouring  to  explain  the  occurrence  of  certain 
common  European  species  in  unexpected  localities  abroad. 
When  this  snail  was  first  discovered  in  North  America,  its 
presence  there  was  universally  attributed  to  the  action  of  man, 
and  was  often  cited  as  a  good  instance  of  the  facility  with 
which  terrestrial  mollusks  are  introduced  into  foreign  coun- 
tries and  become  established  there.  Until  the  year  1864  no 
other  theory  was  even  thought  of.  During  that  year,  however, 


*  Scharff,  E.  F.,    "  On  a  former  Land  Bridge  between  Europe  and 
North  America." 


14  ORIGIN   OF   LIFE   IN   AMERICA 

Professor  E.  Morse  first  discovered  the  shell  of  this  snail 
among  the  contents  of  ancient  'k  kitchen-middens,"  those 
peculiar  refuse  heaps  of  primitive  man,  on  some  of  the  islands 
off  the  east  coast  of  Maine.  He  pondered  over  this  singular 
mystery  and  finally  came  to  the  conclusion  that  the  snail  must 
have  slowly  wandered,  during  a  long  series  of  centuries,  from 
the  Old  World  to  the  New,  by  means  of  an  ancient  North 
Atlantic  land  bridge.  Mr.  Johnson,*  to  whose  instructive 
paper  I  am  indebted  for  this  information,  states  that  Dr. 
Binney  and  Professor  Cockerell  concurred  in  Professor 
Morse's  opinion.  He  also  informs  us  that  the  Rev.  Winkley 
and  he  were  of  opinion  that  the  arrival  of  the  snail  Helix 
hortensis  in  America  must  have  taken  place  before  the  advent 
of  the  Glacial  Epoch. 

This  theory,  as  can  be  imagined,  was  by  no  means  gene- 
rally accepted  in  America.  All  doubts,  however,  as  to 
the  claim  of  Helix  hortensis  being  an  indigenous  American 
species  are  now  set  at  rest,  through  the  discovery  by 
Dr.  Dall  f  of  the  shell  of  this  snail  in  undoubtedly  Pleisto- 
cene deposits  in  the  State  of  Maine.  Some  naturalists  might 
still  be  inclined  to  urge  that  greater  facilities  for  occasional 
transport  across  the  Atlantic  may  have  existed  in  those  remote 
times  than  at  present,  and  that  the  argument  in  support  of 
a  land  bridge  is  not  convincing.  No  evidence,  however,  in 
favour  of  an  ocean  current  from  Europe  to  North  America  in 
Pleistocene  times  has  as  yet  been  brought  forward,  while  the 
conviction  in  the  former  presence  of  a  land  connection  between 
north-eastern  America  and  north-western  Europe  is  based 
upon  other  biological  observations.  From  a  geological  point 
of  view  we  can  scarcely  hope  to  be  able  to  determine  the  period 
or  periods  during  which  this  land  bridge  existed.  The  bathy- 
metrical  features  of  the  north  Atlantic,  according  to  Pro- 
fessor Hull,J  Dr.  Spencer  §  and  Dr.  Nansen,||  point  to  a  pre- 
Glacial  elevation  of  the  land  in  northern  latitudes.  Dr. 


*   Johnson,  C.  W.,  "  Distribution  of  Helix  hortensis,"  p.  73. 

t  Dall,  W.  H.,  "  Land  and  Freshwater  Mollusks  of  Alaska,"  p.  20. 

J   Hull,  E.,  "  Submerged  Terraces  and  .River  Valleys." 

§  Spencer,  J.  W.,  "  Submarine  Valleys,"  p.  224. 

||  Nansen,  F.,  "North  Polar  Expedition,"  p.  192.      • 


ON   THE    CAUSE   OF    THE   ICE   AGE  15 

Wright  *  and  Mr.  Upham,  two  well-known  authorities  on 
glacial  phenomena  expressed  the  view  that  the  northern  lands 
must  have  been  gradually  elevated  in  Pliocene  times,  be- 
coming continuous  before  the  Ice  Age.  Further  particulars 
on  this  subject  are  contained  in  Dr.  Spencer's  articlef  on 
high  continental  elevation. 

Sir  Henry  Howorth  opposes  this  view,  urging  that  Green- 
land, Scandinavia,  and  North  America  were  all  at  a  much 
lower  level  in  so-called  Glacial  times  than  they  are  now.  If 
this  be  so,  then  the  epeirogenic  theory  has  no  base  to  stand 
upon.  I  do  not  think  that  Sir  Henry  Howorth's  J  statement 
is  applicable  to  southern  Greenland  or  eastern  North  America. 
At  any  rate,  it  is  not  contended  by  anyone  that  the  high  level 
condition  of  these  countries  persisted  during  the  whole  of 
the  Ice  Age. 

The  theory  that  the  Ice  Age  or  Glacial  Epoch  was  brought 
about  mainly  by  the  closing  of  the  Arctic  Ocean  to  the  influence 
of  the  Gulf  Stream  is  a  very  tempting  one.  The  temperature 
of  the  Atlantic  Ocean  would  under  such  conditions  have  been 
higher  than  it  is  now,  because  its  heat  would  not  have  been 
modified  by  cold  arctic  currents,  as  it  is  at  present.  Southern 
Greenland,  Iceland,  and  the  lands  on  both  sides  of  the 
Atlantic  should  also  have  had  a  more  favourable  climate  than 
obtains  under  existing  circumstances,  since  the  warm  ocean 
would  have  had  considerable  influence  upon  their  climate  for 
a  certain  distance  inland.  There  is  evidence,  on  the  European 
side  of  the  Atlantic,  that,  at  a  not  very  distant  geological 
period,  and  presumably  at  a  time  when  the  coasts  of  France, 
south-west  of  England  and  south  of  Ireland  were  still  united, 
the  southern  fauna  and  flora  crept  steadily  northward  along 
the  ancient  shore-line.  That  this  did  not  take  place  in  very 
recent  times  is  evidenced  by  the  fact  that  the  southern  marine 
shore  forms  of  mollusks,  crustaceans  and  other  invertebrates 
have  a  somewhat  discontinuous  range  on  the  west  coast  pf 
the  British  Islands,  and  do  not  occur  in  the  English  Channel 
or  in  the  southern  part  of  the  North  Sea. 


*  Wright,  G.  F.,  and  Warren  Upham,  "  Greenland  Icefields  "  p.  331, 
f  Spencer,  J.  W.,  "  High  Continental  Elevation." 
t  Howorth,  H.  H.,  "Ice  or  Water,"  Vol.  I.,  p.  136. 


16  OBIGIN   OF   LIFE   IN   AMEEICA 

Hence  they  evidently  wandered  northward  under  different 
geographical  conditions  than  exist  at  present,  and  only  main- 
tain a  slender  hold  in  isolated  localities,  where  they  form 
relict  colonies.  I  assume  that  this  northward  advance  of  the 
marine  fauna  took  place  in  late  Pliocene  times  when  the 
northern  Atlantic  was  closed,  and  the  temperature  of  the 
ocean  raised.  As  Dr.  Dall  wrote  to  me  "  the  Pliocene  all  over 
the  northern  hemisphere  was  a  period  of  warmer  sea  water 
than  the  Miocene  or  Pleistocene."  My  attention  was  also 
recently  drawn  by  Professor  Morse*  to  the  fact  that  even 
littoral  European  species  have  extended  their  range  across  the 
ocean  to  North  America.  As  long  ago  as  1855  he  received 
specimens  of  the  common  European  "  Periwinkle  "  (Littorina 
litorea)  from  Chaleur  Bay  in  the  Gulf  of  St.  Lawrence.  Later 
on  this  'mollusk  was  reported  also  to  occur  on  the  coast  of 
Nova  Scotia  and  Labrador.  It  is  steadily  advancing  now  in  a 
southward  direction,  while  it  is  becoming  scarce  in  the  north. 

Dr.  Ash  worth  f  tells  me  that  the  lugworm  (Arenicola 
marina)  which  is  common  on  the  west  coast  of  Europe  is  also 
met  with  on  the  coasts  of  the  Shetland  islands,  the  Faroes, 
Iceland,  Greenland,  Labrador  and  Nova  Scotia.  It  is  absent 
from  the  coasts  of  the  Pacific  Ocean.  Hence  he  concludes 
that  a  continuous  shore-line  formerly  existed  between  the  two 
areas  on  each  side  of  the  Atlantic  Ocean  in  which  this  worm 
is  now  found.  Dr.  Ashworth  believes  that  the  extensive 
stretch;  of  ocean  at  present  existing  between  Europe  and 
America  forms  just  as  much  a  barrier  to  the  dispersal  of 
the  littoral  lugworm  as  it  does  to  that  of  the  terrestrial  Helix 
hortensis  just  alluded  to. 

Commenting  on  this  occurrence  of  European  littoral  marine 
mollusks  on  the  north-east  coast  of  North  America,  Mr.  B.  B. 
Woodward  writes  to  me  that  no  other  theory  than  that  of  the 
previous  existence  and  subsequent  rupture  of  a  land  bridge  I 
in  the  direction  indicated  can  satisfactorily  account  for  the/ 
present  disjointed  distribution  of  the  two  divisions  of  the/ 
boreal  fauna. 

It  was  assumed  by  Professor  NathorstJ  that  a  portion  of 
*  Morse,  E.  S.,  "Dispersion  of  certain  Mollusks,"  p.  8. 
•  Ashworth,  J.  H.,  Catalogue  of  Chaetopoda  part  I. 
|  Nathorst,  A.  G.,  "  Pflanzengeographie  der  Vorzeit,"  p.  267. 


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FAUNA   OF   NORTH   ATLANTIC  17 

the  arctic  flora  had  originated  in  Greenland  in  pre-Glacial 
times  and  had  been  scattered  east  and  west  across  the  exist- 
ing land  bridges  on  the  advent  of  the  Glacial  Epoch,  during 
which  the  maintenance  of  life  was  no  longer  possible  in  that 
country. 

Sir  Joseph  Hooker  *  long  ago  expressed  the  opinion  that, 
although  many  Greenland  plants  were  possibly  destroyed 
during  the  Ice  Age,  the  existing  remnant  of  a  much  richer 
flora  had  survived  in  the  southern  parts  of  the  country,  whence 
it  subsequently  spread  northward  again. 

One  of  the  biological  arguments  I  adduced  in  favour  of  a 
former  north  Atlantic  land  bridge  was  derived  from  the  well- 
known  fact  that  deposits  of  dead  marine  shallow-water  species 
had  been  dredged  in  deep  water  in  various  localities  such  as 
Eockall  Bank  and  off  the  coast  of  Iceland.  This  peculiar 
circumstance  has  been  applied  by  several  authorities  in  sup- 
port of  the  theory  of  a  gradual  sinking  of  the  land,  the 
shallow- water  species  having  thus  been  moved  to  a  position 
in  which  they  are  no  longer  able  to  live.  It  is  this  part  of 
the  biological  argument  on  the  land  bridge  theory  which  has 
received  most  of  the  adverse  criticism.  Dr.  Johansen,f  for 
instance,  pointed  out  that  the  evidence  derived  from  the 
marine  shallow-water  shells  is  untrustworthy,  because  their 
presence  in  great  depths  in  the  northern  Atlantic  is  not  due 
to  a  sinking  of  the  land,  but  mainly  to  various  casual  or 
accidental  activities  of  transport.  The  theory  of  the  north 
Atlantic  land  bridge,  in  so  far  as  it  is  founded  upon  the  occur- 
rence of  shallow-water  marine  shells  at  great  depths,  does 
not,  therefore,  meet  with  his  approval. 

Similarly,  Dr.  Appell^f  J  insists  that  the  most  recent  dis- 
coveries on  the  "  Faroe  Bank  "  are  of  considerable  zoogeo- 
Igraphical  significance,  since  they  are  opposed  in  some 
measure  to  the  theory  of  the  sinking  of  the  land.  He  informs 
us  that  among  the  thick  layer  of  dead  shallow  shells  found 
on  the  Faroe  Bank  living  specimens  of  several  of  the  species 
were  met  with. 

*  Hooker,  J.  D.,  "  Distribution  of  Arctic  Plants,"  pp.  252—255. 
t  Johansen,  A.  0.,  "On  the  Sinking  of  Sea-beds,"  p.  403. 
J  Appeltyf.  A.,  "  Norwegian  Fisheries,"  Vol.  II.,  pp.  83—89. 

L.A.  C 


18  OBIGIN   OF   LIFE   IN   AMEEICA 

No  doubt  this  discovery  provides  an  argument  for  the  op- 
ponents of  the  land  bridge  theory,  yet  we  know  how  adaptive 
certain  species  are  to  a  change  of  conditions,  and  how  long 
they  can  maintain  themselves  under  adverse  circumstances. 
I  am  not,  therefore,  disposed  to  attach  too  much  importance 
to  Dr.  Appell^f  s  discovery.  In  any  case,  the  land  bridge  theory 
is  not  dependent  on  the  evidence  alluded  to. 

Dr.  Spethmann,*  on  the  other  hand,  reiterates  what  we 
already  know,  that  from  a  purely  geological  standpoint  there 
are  no  positive  proofs  in  favour  of  a  former  land  bridge 
between  Europe  and  Greenland. 

These  seem  to  be  the  principal  arguments  that  have  been 
advanced  in  opposition  to  the  land  bridge  theory,  and  they 
are,  in  my  opinion,  not  very  formidable  ones. 

The  question  of  the  supposed  survival  of  plants  through 
the  Ice  Age  in  Greenland  is  closely  connected  with  that  of 
the  land  bridge  alluded  to.  Whether  any  plants  survived,  and 
what  proportion  of  those  previously  existing,  largely  depends 
on  the  nature  of  the  Ice  Age  or  Glacial  Epoch  and  on  the 
former  extension  of  the  glaciers  in  Greenland.  Professor 
James  Geikie  f  maintains  that  it  is  a  fair  assumption  that 
the  ice  of  Greenland  in  Glacial  times  completely  buried  the 
land  and,  perhaps,  protruded  beyond  it.  It  has  recently  been 
very  clearly  demonstrated,  however,  by  the  leader  of  the 
German  Greenland  Expedition,  Dr.  E.  von  Drygalski,J  that 
the  strip  of  land  now  free  from  ice  on  the  west  coast  of  Green- 
land has  never  been  entirely  invaded  by  glaciers.  No  doubt 
it  can  be  proved,  he  remarks,  that  the  ice  in  past  times  had 
a  greater  extension.  All  the  same,  glaciers  never  reached  the 
cliffs  and  rock  pinnacles  which  abound  on  all  parts  of  the 
coast  land  of  Greenland. 

No  special  reason  can  be  adduced,  therefore,  why  the  pre- 
sent flora  of  Greenland  should  not  have  survived  the  Ice  Age 
in  that  country,  particularly  as  we  have  some  grounds  for  the 
belief  that  the  land  in  parts  of  the  Arctic  Regions  then  stood 
higher  than  it  does  now,  and  that  consequently  more  land  was 

*  Spethmann,  H.,  "  Aufbau  d.  Insel  Island,"  p.  8 

t  Geikie,  J.,  "  The  Great  Ice  Age,"  p.  736. 

|  Drygalski,  E.  von,  "  Grdnland  Expedition,"  Vol.  I.,  p.  385. 


DID   ANIMALS    SUKVIVE    THE    ICE   AGE?        19 

available  for  plant  life.  Indeed,  Professor  Vanhoffen  *  who 
describes  the  plants  and  animals  observed  during  the  expedi- 
tion, adopts  this  attitude.  He  not  only  believes  in  the  survival 
of  the  flora  of  Greenland  through  the  Ice  Age,  but  he  also 
argues  that  the  great  mass  of  the  fauna  is  indigenous  to  the 
country. 

Though  he  does  not  deny  the  possibility  of  organisms 
being  accidentally  carried  by  birds,  and  other  occasional 
means  of  transport,  he  protests  against  the  assumption  that 
the  fauna  of  Greenland,  as  a  whole,  owes  its  origin  to  such 
a  mode  of  conveyance.  Dr.  Brehmf  quite  concurs  in  this 
view.  He  is  convinced  that  the  fauna  of  Greenland  is 
autochthonous. 

It  is  very  generally  believed  that  the  climate  of  Greenland 
was  much  colder  during  the  Glacial  Epoch  than  it  is  now, 
although  we  possess  no  direct  evidence  that  it  was  so.  A 
mild  climate  in  South  Greenland  during  the  existence  of  the 
land  bridge  is  implied  by  the  fact  that  a  number  of  Euro- 
pean species  found  in  north-western  North  America,  and 
which  no  doubt  travelled  by  way  of  Greenland,  have  since 
become  extinct  in  the  latter  country. 

Greenland  must,  therefore,  have  passed  through  a  phase 
during  which  existence  became  impossible  for  these  species. 
Yet,  for  all  we  know,  it  may  be  only  quite  recently  that  the 
climate  of  Greenland  has  grown  so  inhospitable.  It  has  been 
suggested  by  Professor  Whitney,  and  more  recently  by  Sir 
Henry  Howorth,  that  the  Arctic  Kegions  enjoyed  temperate 
conditions  during  the  Glacial  Epoch  and  are  only  now  passing 
through  the  more  severe  post-Glacial  stage.  In  view  of  the 
accumulation  of  evidence  pointing  to  a  southward  advance 
of  the  Arctic  fauna  and  flora  in  Pleistocene  times,  such  a  sug- 
gestion may  seem  contrary  to  biological  evidence.  I  shall 
endeavour  to  show,  however,  in  the  next  few  chapters  that 
we  possess  a  good  deal  of  valuable  testimony,  principally  of 
a  biological  nature,  in  support  of  Professor  Whitney's  and  Sir 
Henry  Howorth's  contention. 

With  regard  to  the  species  which  I  believe  to  have  made  use 

*  Vanhoffen,  E.,  "  Gronland  Expedition,"  Vol.  II.,  p.  174. 

t  Brehm,  V.,  "  Entomostraken  d.  Danmark  Expedition,"  p.  316. 

c  2 


20  ORIGIN   OF   LIFE   IN   AMERICA 

of  the  ancient  north  Atlantic  land  connection,  and  are  sup- 
posed to  have  subsequently  become  extinct  on  the  intermediate 
stations  between  the  two  continents,  particular  attention  may 
be  drawn  to  the  range  of  the  "  running  beetles  "  of  the  genus 
Carabus.  They  are  of  great  value  in  aiding  us  to  solve  pro- 
blems of  this  nature,  because,  being  usually  found  under 
stones  and  clods  of  earth,  they  are  not  liable  to  oc<?asional 
transport  by  floods.  Being  wingless  they  cannot  be  carried 
to  distant  lands  by  winds ;  and  lacking  any  kind  of  means  by 
which  they  might  become  attached  to  a  mammal  or  bird  they 
would  not  be  conveyed  in  such  an  accidental  manner  from  one 
locality  to  another.  The  great  importance  of  the  species  of 
Carabus  has  been  recognised,  and  their  distribution  brought 
to  bear  upon  zoogeographical  problems  by  Mr.  Born.*  He  cites 
two  of  the  species,  viz.,  Carabus  catenulatus  and  Carabus 
nemoralis,  as  evidences  of  a  former  land  bridge  between 
northern  Europe  and  North  America,  although  they  no  longer 
occur  in  Iceland  or  in  Greenland.  Both  these  running  beetles 
are  typically  European  species,  being  quite  absent  from  Asia. 
The  conspicuously  ornamental  Carabus  memoralis  is  confined 
in  North  America,  to  Nova  Scotia  and  New  Brunswick.  Hence 
it  somewhat  agrees  in  its  American  range  with  that  of  Helix 
hortensis.  The  other  species  of  Carabus  has  a  wider  dis- 
tribution in  boreal  North  America. 

Such  instances  lead  us  to  believe,  therefore,  that  the  faunas 
of  Greenland  and  Iceland  were  richer  in  pre-Glacial  times 
than  at  present.  They  are  certainly  suggestive  also  of  a  sur- 
vival of  species  having  taken  place  through  the  Ice  Age  within 
the  glaciated  area  of  North  America.  We  possess  no  evidence 
that  these  beetles  and  the  snail  Helix  hortensis,  and  many 
other  animals  belonging  to  the  same  group  of  European  in- 
vaders, were  pushed  south  during  Pleistocene  times  into  the 
United  States,  and  that  they  then  regained  their  former 
northern  habitat,  after  having  become  extinct  again  in  their 
more  southern  stations. 

The  extinction  of  a  large  part  of  the  former  beetle  fauna 
of  Greenland  may  be  inferred  from  the  fact  that  Greenland 
only  possesses  forty-one  species  of  beetles,  while  there  are 

*  Born,  P.,  "  Zoogeographisch-carabologische  Studien,"  p.  8. 


THE    SNAILS   OF   GEEENLAND  21 

ninety-one  in  Iceland.*  Of  the  more  hardy  spiders  the  per- 
centage of  survival  is  very  different,  for  there  are  fifty-three 
species  in  Greenland  and  only  twenty-four  in  Iceland. "j* 

The  theory  of  the  survival  of  species  in  Greenland  may 
be  tested  by  some  other  examples.  Besides  Helix  hor- 
rfcensis  about  a  dozen  other  kinds  of  land  and  fresh- 
water mollusks  inhabit  the  country.  J  Eight  of  these  either 
have  their  centre  of  distribution  in  Greenland  or  are 
quite  peculiar  to  the  country.  These  are  Planorbis  nathorsti, 
P.  arcticus,  Limnaea  vahli,  L.  holbolli,  Succinea  groen- 
landica,  Vitrina  angelicae,  Conulus  fabricii  and  Pupa  hoppii. 
The  two  species  of  Planorbis  are  also  known  from  Labrador ; 
Succinea  groenlandica  occurs  in  Iceland ;  P.  arcticus  has 
been  met  with  in  Scandinavia,  Finland  and  Siberia.  The 
first  of  the  Limnaeas  ranges  from  Greenland  to  Alaska, 
the  other  is  peculiar  to  Greenland.  The  latter,  however, 
is  replaced  in  boreal  North  America  by  the  closely-allied 
Limnaea  retusa.  Vitrina  angelicae  is  not  found  in  America, 
but  occurs  in  Iceland  and  Norway.  Conulus  fabricii  is  pro- 
bably only  a  variety  of  the  common  Conulus  f  ulvus  of  northern 
Europe,  Asia  and  America,  while  Pupa  hoppii  is  confined  to 
Greenland.  With  the  single  exception  of  Planorbis  arcticus 
all  these  species  live  at  present  well  within  the  glaciated  area, 
that  is  to  say,  within  that  portion  of  the  northern  regions 
supposed  to  have  been  either  wholly  or  partially  buried  by 
ice  during  the  Glacial  Epoch.  As  none  but  Planorbis  arcticus 
have  ever  been  found  fossil  outside  that  area,  we  may  assume 
with  some  justification  that  most  of  them  originated  in  Green- 
land, and  that  all,  at  any  rate,  survived  the  Ice  Age  in  that 
country.  Planorbis  arcticus,  as  Mr.  Kennard  §  informs  me, 
has  been  taken  in  Pleistocene  deposits  in  Denmark  and  in 
the  south  of  England.  (Compare  also  Kennard  and  Wood- 
ward's paper.) 

It  is  more  difficult  to  demonstrate  that  butterflies  and  moths 


*  Poppius,  B.,  "  Coleopteren  des  Arktischen  Gebietes/'  p.  428. 
t  Strand,  E.,  "  Arktische  Araneae,"  p.  436. 

t  Morch,  0.  A.  L.,  "  Land  and  Freshwater  Mollusca  of  Greenland." 
§  Kennard,   A.    S.,    and   B.    B.    Woodward,    "  Extinct  post-pliocene 
Mollusca  of  Southern  England,"  p.  5. 


22  ORIGIN   OF   LIFE   IN   AMERICA 

have  survived  the  Glacial  Epoch  in  Greenland,  yet  several 
authors  who  have  written  on  the  lepidopterous  fauna  of  that 
'country  maintain  that  the  theory  of  a  former  land  bridge 
with  Europe  and  North  America  is  quite  consistent  with  the 
facts  of  distribution.  Mr.  Petersen,*  for  example,  concludes 
from  his  studies  that  land  connections  in  high  northern  lati- 
tudes enabled  certain  arctic  butterflies  and  moths  to  spread 
from  a  polar  centre  to  Europe  and  North  America.  After 
alluding  to  a  large  number  of  moths  common  to  Canada  and 
Europe,  Mr.  Girard  f  emphasises  the  significance  of  this  fact 
as  indicating  the  former  existence  of  a  land  bridge  between 
North  America,  Greenland  and,  Europe. 

Although  no  butterflies  occur  in  Iceland,  Coleas  nastes, 
Argynnis  chariclea  and  A.  polaris  are  known  even  from  the 
barest  and  most  exposed  districts  of  Greenland,  where 
nothing  but  Dryas  octopetala  and  some  slender  grasses  grow. 
These  species  have  a  wide  range  in  boreal  America,  Europe 
and  Asia,  but  of  the  nine  butterflies  known  from  the  arctic 
American  archipelago  five  are  European,  while  only  two  are 
met  with  in  Asia,  according  to  Dr.  Pagenstecher.  Many 
striking  examples,  showing  the  relationship  between  Green- 
land and  the  neighbouring  continents  occur  among  the  moths, 
especially  among  the  Noctuidae.  Anarta  melanopa  inhabits 
only  Colorado,  the  White  Mountains,  Labrador,  Scandinavia, 
Scotland  and  the  Alps.  Anarta  leucocycla  and  A.  lapponica 
are  found  in  Labrador,  Greenland  and  Scandinavia.  Mr. 
Grote  J  alludes  to  no  less  than  twenty-eight  other  Noctuids 
that  are  common  to  Europe  and  North  America,  even  ex- 
cluding those  met  with  in  Labrador  or  circumpolar  species. 
All  these  facts  tell  in  favour  of  the  view  I  have  endeavoured 
to  elucidate. 

No  matter  what  group  of  terrestrial  invertebrates  we 
choose,  similar  close  relationships  may  be  discovered  between 
American  and  European  species,  which  cannot  be  explained 
by  the  assumption  of  a  former  land  connection  across  Bering 

*  Petersen,  W.,  "  Lepidopteren-fauna  d.  arkt.  Gebietes,  p.  44. 
t  Girard,    Maurice,     "  L'Entomologie     de     PAmerique    du    Nord," 
p.  287. 

|  Grote,  A.,  "Noctuidae  of  North  America,"  p.  313. 


POLAK  ORIGIN   OF   LIFE  23 

Strait   alone.      Mr.    Emerton  *   makes   mention   of  several 
instances   among   spiders. 

Such  cases  can  be  traced  among  earth-worms,  beetles,  wood- 
lice,  ants  and  other  groups.  In  some  cases  the  identity  or. 
similarity  of  species  occurring  on  the  two  continents  may  be 
due  to  the  fact  that  the  species  originated  in  Greenland  or 
some  polar  centre,  no  longer  in  existence,  and  subsequently 
travelled  in  different  directions  towards  their  present  habitat. 
This  conception,  however,  has  very  little  in  common  with  that 
of  a  polar  origin  of  life  which  was  first  mooted  by  Dr.  Allen. f 
He  argued  that  the  northern  circumpolar  lands  may  be  looked 
upon  as  the  base  or  centre  from  which  have  spread  all  the 
more  recently  developed  forms  of  mammalian  life. 

A  few  years  later  Dr.  Haacke  J  directed  attention  to  the 
peculiar  circumstance  that  the  most  primitive  orders  of 
mammals  and  birds  all  have  their  living  representatives 
in  outlying  areas  of  the  southern  hemisphere,  such  as 
Australia,  New  Zealand,  Madagascar,  South  Africa  and 
South  America,  notwithstanding  that  these  animals  are 
known  to  have  formerly  inhabited  the  northern  hemis- 
phere. This,  he  thinks,  implies  that  a  southward  re- 
treat has  taken  place  of  the  more  ancient  forms  before 
the  advancing  host  of  higher  orders  of  life.  It  would 
seem,  therefore,  as  if  streams  of  more  and  more  highly 
specialized  orders  of  mammals  and  birds  had  been  slowly 
evolved  in  the  north  and  had  constantly  pressed  the  older  ones 
southward.  -This  suggested  to  Dr.  Haacke  the  idea  of  a  polar 
continent  from  which  the  various  orders  had  gradually  been 
distributed  across  the  continents.  Dr.  Wilser  §  even  assumes 
a  polar  origin  for  man. 

A  similar  theory  was  pronounced  by  Canon  Tristram  ||  in 
explanation  of  the  present  distribution  of  the  higher  groups  of 
birds  and  their  migrations.  The  migratory  instinct,  he  con- 
tended, was  due  to  their  having  originated  in  a  polar  centre 

*  Emerton,  J.  H.,  "Spiders  common  to  New  England  and  Europe," 
p.  129. 

t  Allen,  J.  A.,  "Geographical  Distribution  of  Mammals,"  p.  37o. 

I  Haacke,  W.,  "  Nordpol  als  Schopfungszentrum." 

§  Wilser,  L.,  "  Der  Nordische  Schopfungsherd,"  p.  134. 

||  Tristram,  H.  B.,  "Polar  Origin  of  Life." 


24  OEIGIN   OF   LIFE   IN   AMERICA 

and  having  subsequently  been  dispersed  southward  by  different 
routes.  He  believed  that  the  tendency  of  birds  to  migrate 
northwards  was  due  to  a  natural  instinct  to  return  to  the 
home  of  their  ancestors. 

What  I  chiefly  endeavoured  to  prove  in  this  chapter  was  the 
existence  in  pre-Glacial  and  early  Glacial  times  of  a  land 
bridge  joining  Scotland,  Iceland,  Greenland  and  Labrador. 
The  evidence  in  favour  of  such  a  land  connection  must  be 
largely,  if  not  entirely,  biological ;  but  the  testimony,  as  far 
as  it  goes,  leads  me  to  believe  that  the  theory  is  well  founded. 
I  shall  allude  to  a  similar  land  connection  in  another  chapter 
which  probably  joined  North  America  and  Asia.  If  the 
climatic  changes  ushered  in  by  the  Glacial  Epoch  were  pro- 
duced by  the  closing  of  these  two  highways  to  the  Arctic' 
Ocean,  it  is  evident  that  the  preceding  warm  period  must 
have  been  due  to  a  greater  flow  of  warm  currents  to  the  Arctic 
Eegions. 

A  few  years  ago  I  drew  attention  to  the  fact  that  the  animals 
and  plants  found  on  the  Faroes  and  Iceland  in  particular 
imply  the  existence  of  a  former  land  connection  between  Scot- 
land and  the  latter  country.  The  occurrence  in  Iceland  of  the 
European  field-mouse  (Mus  sylvaticus),  of  the  snail  Arianta 
arbustorum,  which  also  inhabits  the  Faroes,  of  the  beetle 
Nebria  gyllenhali,  which  likewise  inhabits  Greenland,  and 
many  other  forms  not  likely  to  have  been  conveyed  by  acci- 
dental means,  all  favour  the  view  that  the  fauna  of  Iceland 
owes  its  existence  mainly  to  the  land  "bridge  referred  to.  But, 
as  I  pointed  out,  Iceland  also  possesses  a  distinctly  American 
element  in  the  snail  Succinea  groenlandica  and  others,  while 
some  of  the  American  plants  have  even  invaded  the  continent 
of  Europe  by  the  Greenland -Iceland  land  bridge.  One  of  the 
objections  raised  against  this  view  is  that  the  low  tempera- 
ture in  the  north  would  have  prevented  any  faunistic  inter- 
change across  the  land  bridge.  Tihe  temperature,  on  the  con- 
trary, in  Iceland,  southern  Greenland,  Labrador  and  Scot- 
land would  have  been  considerably  higher  under  such  geo- 
graphical conditions  than  it  is  now.  If  go,  why  should  not  the 
whole  fauna  of  northern  North  America  have  streamed  across 
this  bridge  to  Europe  and  that  of  northern  Europe  to  North 
America  ?  If  we  examine  the  fauna  of  Canada  we  find  that  it 


FAUNISTIC  AFFINITIES  25 

is  largely  composed  of  Siberian  immigrants.  It  is  possible  that 
these  only  began  to  enter  North  America  from  the  extreme 
west  at  the  time  when  Labrador  was  already  joined  to  Green- 
land. Moreover,  we  may  assume  that  as  soon  as  the  North 
Atlantic  land  connection  excluded  the  Gulf  Stream  from  the 
Arctic  Ocean,  glaciers  began  to  gather  on  all  the  mountain 
ranges  surrounding  the  northern  parts  of  the  ocean,  thus 
preventing  many  forms  of  animal  life  from  taking  advantage 
of  the  facilities  afforded  by  the  land  bridge  of  passing  from  the 
one  continent  to  the  other.  The  greater  warmth  on  the 
northern  coasts  led  to  greater  evaporation  of  sea  water  and 
more  ample  condensation  of  moisture  on  the  elevated  lands 
surrounding  the  ocean.  All  this  will  be  more  fully  discussed 
in  the  succeeding  chapters. 

Apart  from  the  authorities  already  cited  who  expressed 
themselves  in  favour  of  a  north  Atlantic  land  connection, 
between  northern  Europe  and  North  America,  Professor 
Lobley,*  Dr.  Brown,f  Mr.  Grant  J  and  Mr.  Krishtafovitch  § 
have  all  urged  the  same  view  on  different  grounds. 

*  Lobley,  J.  L.,  "  American  Fauna  and  its  Origin,"  p.  26. 

t  Brown,  A.  E.,  "  American  Big  Game,"  p.  87. 

|  Grant,  M.,  "Mammals  of  North  America,"  p.  12. 

§  Krishtafovitch,  N.  J.,  "La  derniere  periode  glaciaire,"  p.  296. 


CHAPTER  II 

NORTH  EASTERN  NORTH  AMERICA 

CROSSING  Davis  Strait  from  southern  Greenland  to 
Labrador,  we  land  in  a  country  whose  barren  headlands  look 
just  as  stern  and  uninviting  as  those  on  the  opposite  side  of 
the  Strait.  But  whereas  the  west  coast  of  Greenland  pre- 
sents a  shore-line  varying  between  rugged  precipices  and 
undulating  plains,  the  whole  sea-front  of  Labrador,  for  over 
a  thousand  miles,  rises  abruptly  from  sea-level  to  a  height 
of  about  1,000  feet  or  more.  Labrador  presents  an  irregular 
plateau  with  a  general  elevation  of  from  1,500  to  2,000  feet 
above  ,sea-level  (see  Fig.  1).  It  forms  part  of  the  oldest 
known  land  on  the  continent  of  North  America,  and,  so  far 
as  we  know,  it  has  never  been  entirely  covered  by  the  sea 
since  very  remote  geological  times.  The  rocks  are  largely 
metamorphic  with  ancient  igneous  intrusions  greatly  resem- 
bling those  of  Greenland,  which,  like  Labrador,  is  a  fragment 
of  that  ancient  continent  to  which  Professor  Suess  applied 
the  name  "  Laurentia."  * 

A  cold  current  of  water  loaded  with  icebergs  from  the 
Arctic  Ocean  sweeps  down  the  east  coast  of  Labrador.  Off 
the  coast  of  Newfoundland  it  meets  a  branch  of  the  Gulf 
Stream,  thus  producing  the  dense  fogs  so  characteristic  of 
the  Grand  Banks.  This  arctic  current  is  mainly  responsible 
for  the  inhospitable  nature  of  the  Labrador  coast. 

The  vegetation  is  mostly  stunted  in  character.  The  dwarf 
birch  (Betula  nana),  the  mountain-ash,  alder  and  some 
willows  here  and  there  form  small  woods,  while  many  of  the 
familiar  Greenland  flowers  reappear.  Yet  the  flora  is  dis- 
tinctly richer  than  that  of  Greenland.  Even  close  to  the  coast, 
in  sheltered  ravines,  occasional  specimens  of  the  white  spruce, 
which  is  more  hardy  than  the  black  spruce,  are  noticeable. 

*  Suess,  E.,  "  Antlitz  der  Erde,"  Vol.  III.2,  p.  284. 


ANIMALS   OF   LABEADOE  27 

To  some  of  those  who  landed  on  the  coast  and  explored  the 
nooks  and  valleys,  the  country  seemed  full  of  beauty,  of 
attractiveness,  and  even  of  a  rich  and  appealing  fertility.  At 
certain  times  it  presents  an  amazing  wealth  of  strikingly 
coloured  flowers.  So  thickly  sown  are  they  that  at  certain 
seasons  they  remind  one  of  a  cultivated  garden.* 

Once  we  leave  the  coast  region  and  enter  the  interior  of 
Labrador,  the  climate  becomes  less  arctic  in  character  and 
timber  increases  in  quantity.  In  fact  there  are  two  distinct 
climates  in  Labrador,  the  arctic  on  the  coast,  the  north  tem- 
perate in  the  interior. 

According  to  Dr.  Packard,f  the  Greenland  and  arctic  forms 
of  animal  and  plant  life  occurring  on  the  coast  are 'the 
remnants  of  the  glacial  or  arctic  fauna  and  flora  which,  being 
formerly  spread  over  the  entire  territory  of  British  America 
and  the  north-eastern  United  States,  still  retain  their  hold 
on  the  treeless  and  exposed  islands  and  headlands  of 
Labrador.  In  many  respects  the  Labrador  fauna  and  flora 
resemble  those  of  trie  far  distant  White  Mountains  in  New 
Hampshire,  as  we  shall  learn  later  on  (p.  35). 

When  we  survey  the  fauna  of  the  coast  of  Labrador  more 
closely  we  find  that,  besides  the  Greenland  or  arctic  element, 
another  much  richer  one  has  apparently  invaded  the  territory 
previously  occupied  by  the  former.  This  new  fauna  becomes 
more  and  more  abundant  as  we  proceed  westward  and  south- 
ward. Thus  the  existence  of  the  barren-ground  caribou  of 
Labrador  which  resembles  the  reindeer  of  Greenland,  is 
threatened  by  enemies  such  as  the  glutton  or  wolverine  (Gulo 
luscus),  and  these  do  not  penetrate  farther  north.  Occa- 
sionally the  Canadian  porcupine  (Erethizon  dorsatus)  has 
been  noticed  in  the  coastal  territory.  Besides  the  lemming 
(Dicrostonyx  hudsonius),  which  is  probably  identical  with 
the  Greenland  form,  quite  an  assembly  of  distinct  ground 
rodents  make  their  appearance,  among  them  Synaptomys 
innuitus,  Microtus  enixus,  Microtus  pennsylvanicus,  Evo- 
tomys  ungava,  Evotomys  proteus,  Zapus  hudsonius,  and 
Peromyscus  maniculatus,  also  the  arctic  fox,  red  fox,  several 

*  Grenfell,  W.  T.,  "  Labrador,"  pp.  393—395. 
t  Packard,  A.  S.,  "  The  Labrador  Coast,"  p.  194. 


28  ORIGIN   OF   LIFE   IN   AMERICA 

small  carnivores  and  a  variety  of  the  black  bear  (Ursus 
americanus).* 

The  small  mouse-like  -creatures  belonging  to  the  genus 
Synaptomys  are  aptly  called  "  lemming-voles  "  because,  ex- 
ternally like  lemmings,  their  teeth  approach  those  of  voles. 
When  Dr.  Merriam  undertook  his  revision  of  the  species  of 
Synaptomys, f  seven  kinds  were  known  to  him.  A  few  more 
have  since  been  discovered.  The  genus  is  entirely  confined  to 
the  North  American  continent,  and  all  the  species  except  two 
have  a  limited  range  in  the  boreal  region.  One  of  the  latter 
(Synaptomys  cooperi)  is  found  from  Massachusetts  westward 
to  Minnesota  and  southward  to  North  Carolina,  the  other  is 
peculiar  to  Mount  Washington.  Almost  all  the  other  species 
are  confined  to  Canada  and  Alaska.  It  does  not  seem,  there- 
fore, as  if  Synaptomys  innuitus,  which  inhabits  the  coast  of 
Labrador,  were  a  recent  immigrant  from  the  south.  On  the 
contrary,  the  genus  Synaptomys,  being  almost  confined  to  the 
north,  is  probably  of  boreal  American  origin,  one  adaptable 
species  having  advanced  far  southward  along  the  east  coast 
of  America. 

The  next  two  species  alluded  to,  Microtus  enixus  and  M. 
pennsylvanicus,  are  true  voles,  though  the  last-named  animal 
is  generally  known  in  the  States  by  the  name  of  "  meadow- 
mouse."  Both  of  them  belong  to  a  sub-genus  which  is 
very  widely  spread  in  Europe,  Asia  and  boreal  North 
America.  J  Some  migrations  across  ancient  land  connections 
must  have  taken  place,  no  matter  whether  we  assume  that  the 
sub-genus  is  of  Old  World  or  New  World  origin.  It  only 
remains  for  us  to  determine  whether  Microtus  crossed  the 
North  Atlantic  land  bridge  or  the  one  supposed  to  have  been 
situated  at  Bering  Strait,  assuming  that  there  was  such  a  one. 
Professor  Tullberg  thought  the  members  of  the  genus  Microtus 
had  travelled  to  America  in  Pliocene  times  by  means  of  the 
first  land  bridge.  §  This  view  does  not  appear  to  me  pro- 
bable, because  the  family  is  entirely  absent  from  Ireland, 


*  Bangs,  O.,  "  Mammals  of  Labrador." 

t  Merriam,  C.  H.,  "  Revision  of  Synaptomys." 

\   Bailey,  V.,  "  Revision  of  Microtus." 

§  Tullberg,  Tycho,  "  System  der  Nagetiere,"  p.  499. 


VOLES   AND   JUMPING-MICE  29 

Iceland  and  Greenland.  There  is  no  fossil  evidence  that  voles 
ever  lived  in  any  of  these  countries,  where  we  might  expect 
them  to  have  survived  had  any  extensive  migration  taken  place 
from  Great  Britain  to  North  America.  Neither  in  Europe  nor 
in  North  America  are  there  any  fossil  remains  of  the  sub- 
genus  Microtus  older  than  Pleistocene,  if  we  accept  Mr. 
Barnum  Brown's  estimate  of  the  age  of  the  Potter  Creek 
deposits.*  Nevertheless,  it  is  possible  that  these  voles  origi- 
nated in  North  America  long  prior  to  the  Pleistocene  Period. 
If  so  I  believe  they  made  use  of  the  Bering  Strait  land  con- 
nection rather  than  the  North  Atlantic  one,  in  passing  from 
the  New  World  to  the  Old. 

Evotomys,  another  genus  found  in  the  coastal  district  of 
Labrador,  has  a  range  somewhat  similar  to  that  of  Microtus. 
It  is  closely  allied  to  it  and  scarcely  deserves  the  name  of 
"red-backed  mouse  "  as  the  Americans  call  it,  because  it  is 
distinctly  a  vole,  without  any  mouse -like  characters  about  it. 
The  relationship  between  the  American  and  Old  World  forms, 
as  in  the  case  of  Microtus,  must  be  du©  to  the  existence  of  a 
former  land  bridge  across  Bering  Strait. 

The  jumping-mice  (Zapus),  to  which  Zapus  hudsonius 
belongs,  are,  in  many  respects,  an  interesting  group  of 
rodents.  Somewhat  kangaroo -like  in  their  movements,  they 
are  almost  entirely  confined  to  boreal  North  America.  The 
Labrador  jumping-mouse  is  a  variety  of  Zapus  hudsonius, 
which  ranges  from  Alaska  to  Labrador  and  New  York.  A 
single  species  of  jumping-mouse  (Zapus  setchuanus)  occurs  in 
China. f  The  theory  that  a  former  land  bridge  across  Bering 
Strait  enabled  its  ancestors  to  traverse  the  northern  Pacific 
seems  quite  evident  in  this  case.  Yet  we  must  not  forget  that 
the  American  jumping-mice  also  have  somewhat  more  dis- 
tant relations  in  the  Old  World,  the  jerboas,  from  which  the 
remote  ancestors  of  Zapus  may  possibly  have  descended. 

We  need  not  at  present  deal  with  the  other  rodents  or  the 
carnivores  found  in  the  coast  district  of  Labrador,  as  most  of 
these  will  be  referred  to  again  in  subsequent  chapters.  The 
animals  that  have  just  been  alluded  to  show  us  that  the 

*  Brown,  Barnum,  "  Conard  fissure,"  p.  208. 

f  Preble,  E.  A.,  "  Revision  of  the  Jumping  Mice%" 


30  ORIGIN   OF   LIFE   IN    AMERICA 

Labrador  fauna  is  largely  composed  of  indigenous  American 
species,  which  have  not  penetrated  to  Greenland.  This  seems 
to  suggest  that  the  points  of  resemblance  in  the  fauna  of 
Labrador  and  Greenland  may  have  been  more  marked  in 
remoter  times,  before  the  influence  of  the  continental  fauna 
had  impressed  itself  upon  the  outlying  peninsula  of  Labrador. 
Considering  the  extreme  probability  of  Labrador  having  been 
connected  by  land  with  Europe  by  way  of  Greenland  and 
Iceland  in  Pliocene  times,  we  might  expect  some  Euro- 
pean mammalian  types  to  have  occurred  in  north-eastern 
North  America.  The  little  evidence  we  possess  tends  to 
show  that  the  mamtaialian  life  of  the  extreme  north  of 
western  Europe  was  always  poor.  We  cannot  assume 
that  insurmountable  barriers  prevented  European  mammals 
from  invading  America,  because  certain  species  such  as  the 
reindeer  and  lemming  seem  to  have  passed  from  America  to 
Europe  across  a  North  Atlantic  land  bridge.  It  might  be 
argued  that  European  animals  did  cross  over,  but  were  unable 
to  maintain  themselves  in  America,  a  fate  which  has  largely 
befallen  the  American  immigrants  in  Europe.  For  such  a 
supposition,  however,  we  still  lack  evidence.  If  no  examples 
of  European  animals  or  plants  were  known  from  the  American 
side  of  the  water,  we  might  assume  the  land  bridge  to  have 
been  a  discontinuous  one,  as  Mr.  Hedley  suggested  to  me, 
connecting  Greenland  alternately  with  Labrador  and  Scotland. 
But  one  of  our  strongest  supports  for  the  North  Atlantic- 
land  bridge  is,  as  I  said,  the  presence  of  the  European 
Helix  hortensis  in  North  America.  It  still  occurs  in 
Labrador.  From  Labrador  it  travelled  southward  along  the 
coast.  Is  it  possible  tfoat  the  whole  strip  of  coast  was  at 
'that  time  cut  off  by  some  barrier  from  the  interior  of 
North  America  ? 

Supposing  the  western  parts  of  the  Labrador  plateau  had 
become  covered  by  glaciers  as  soon  as  the  North  Atlantic  land 
bridge  was  formed,  it  might  have  produced  an  effectual  barrier 
against  western  invaders  and  yet  have  allowed  eastern  forms 
to  reach  Labrador. 

Later  on  I  intend  to  return  to  this  problem  again.  Mean- 
while, let  us  journey  westward  across  the  high  plateau  of 
Labrador  towards  Hudson  Bay  and  Central  Canada.  As  we 


NOBTHEKN   FKOGS  31 

enter  the  vast  forest  region,  plant  life  as  well  as  animal  life 
become  more  and  more  abundant  and  differentiated.  In- 
stead of  the  barren-ground  caribou,  we  now  meet  with  the 
woodland  form  accompanied  by  another  large  ungulate,  the 
moose,  while  the  flying  squirrel,  chipmunk,  the  ground 
squirrel,  woodchuck,  white-footed  mouse,  musk-rat,  beaver, 
skunk,  weasel,  shrews,  moles  and  many  other  beasts  tenant 
the  forests,  meadows,  and  banks  of  rivers.* 

A  few  amphibians,  even,  have  succeeded  in  surviving  the 
rigours  of  the  arctic  winter  of  those  regions,  and  have  success- 
fully established  the  most  northern  outposts  in  eastern  North 
America.  The  leopard  frog  (Eana  pi  pi  ens),  one  of  the 
commonest  as  well  as  one  of  the  most  brilliantly  coloured  of 
American  frogs,  is  one  of  these.  The  pickerel  (Kana  palus- 
tris),  also  the  northern  wood  frog  (Eana  cantabrigiensis) 
and  the  northern  frog  (Eana  septentrionalis)  have  all  been 
observed  in  the  neighbourhood  of  Hudson  Bay.  The  most 
interesting  species  is  the  swamp-tree  frog  (Chorophilus 
nigritus),  whose  northern  variety  has  advanced  into  this  in- 
hospitable region,  though  almost  all  of  the  other  members 
of  the  tree  frog  family  (Hylidae)  are  typically  southern 
forms. f  Whether  newts  occur  in  the  Hudson  Bay  region  is 
not  definitely  known,  but  the  salamander  (Plethodon 
cinereus),  at  any  rate  seems  to  have  been  met  with.  All  these 
species  are  peculiar  to  America. 

No  reptiles  have  been  noticed.  The  distribution  of  the 
terrestrial  mollusks,  the  snails  and  slugs,  implies  that  an  ad- 
vance in  a  northward  direction,  similar  to  that  recorded  in 
the  case  of  mammals  and  amphibians,  has  taken  place  among 
some  groups  of  invertebrates.  The  typically  American  snails, 
Polygyra  monodon  and  Strobilops  labyrinthica,  have  been 
collected  near  Hudson  Bay. 

When  we  analyse  the  constitution  of  all  these  western  and 
southern  groups,  and  trace  the  relationship  of  the  members 
more  carefully,  we  notice  that  many  of  them  are  not  of 
American  ancestry.  They  all  have  lived,  no  doubt,  long 
enough  in  America  to  have  become  thoroughly  established, 

*  Preble,  E.  A.,  "Hudson  Bay  Eegion." 

t  Dickerson,  Mary  C.,  "  The  Frog  Book,"  p.  158. 


32  OKIGIN   OF   LIFE   IN   AMERICA 

being  part  of  the  indigenous  fauna,  yet  we  recognise  that  their 
ancestors  must  have  entered  the  continent  from  Asia  in  com- 
paratively recent  geological  times. 

Let  us  take  for  example  the  moose  deer  (Alces  americanus). 
Its  range  extends  from,  Bering  Strait,  in  a  broad  tract  of  forest 
land  eastward,  along  the  northern  shores  of  the  Great  Lakes 
as  far  as  Nova  Scotia  on  the  Gulf  of  St.  Lawrence.  Only 
along  the  Rocky  Mountains,  as  Mr.  Thompson  Seton  has  so 
clearly  indicated  in  his  map  of  the  range  (Fig.  3),  does  the 
moose  occur  further  south.* 

There  are  a  few  historical  records,  and  also  some  fossil 
ones,  which  indicate  that  the  moose  once  penetrated  further 
into  the  United  States  in  various  directions,  but  it  evidently 
never  diverged  very  much  from  its  present  range.f  The  bones 
of  a  couple  of  closely  allied  animals  have  been  met  with  in  the 
Pleistocene  deposits  of  Washington  territory,  and  the  skeleton 
of  a  peculiar  moose,  somewhat  resembling  the  Alaskan  variety, 
has  been  discovered  in  the  Pleistocene  of  New  Jersey,  and 
placed  by  Professor  Scott  into  a  distinct  genus  (Cervalces). 
Whether  this  animal  was  ancestral  to  the  living  moose,  as 
has  been  suggested,  or  whether  it  represents  an  aberrant 
type  which  has  come  in  from  Siberia  with  the  moose,  as  Mr. 
Grant  seems  to  think  likely,  are  problems  which  may  be 
left  to  future  research es.J  Certain  it  is  that  when  we  cross 
Bering  Strait  into  Northern  Asia,  we  meet  with  a  moose 
(Alces  bedfordiae)  which  in  its  simple  antlers  somewhat 
resembles  the  young  American  moose.  Further  west  as  far  as 
Scandinavia,  we  find  another  species  (A.  machlis)  differing 
but  slightly  from  Alces  americanus.  It  seems  almost  as  if 
the  moose  had  originated  in  eastern  Asia  from  some  more 
generalised  type  like  Alces  bedfordiae,  and  had  gradually 
produced  the  forms  with  more  palmated  antlers  in  America 
and  Europe  by  a  process  of  convergent  evolution.  In  any 
case,  we  are  led  to  assume  that  Bering  Strait  was  dry  land 
when  the  ancestors  of  the  existing  moose  entered  the  New 
World.  Even  if  we  suppose  the  moose  to  have  originated  in 
America,  a  land  bridge  connecting  the  latter  with  Asia  was  a 

*  Seton,  Thompson,  "  Life  Histories  of  Northern  Animals,  L,"  p.  151. 

t  Grant,  Madison,  "Moose." 

%  Grant,  Madison,  "  Origin  and  Relation  of  Mammals,"  p.  23. 


-• 


MOOSE   DEER  33 

necessity.     This  problem  of  the  Bering  Strait  land  bridge, 
however,  will  be  more  fully  discussed  later  on  (pp.  83 — 86). 

The  moose,  or  elk  as  it  is  called  in  Europe,  has  been  stated 
to  occur  in  the  Caucasus,  but  its  range  only  extends  to  the 
forests  north  of  this  mountain  range.  Like  the  reindeer,  it 
occurred  much  further  south  formerly,  even  as  far  as 
northern  Italy,  and  yet  no  theories  as  to  a  former  arctic 
climate  are  founded  on  this  fact.  In  Caesar's  time  the  elk  was 
still  abundant  in  the  Black  Forest  in  southern  Germany, 
while  it  is  now  confined  to  certain  parts  of  Russia  and 
Scandinavia. 

Many  other  American  species  resemble  the  moose  in  their 
range,  except  that  they  manifest  more  clearly  their  Asiatic 
origin.  The  further  west  we  travel  the  more  often  do  we 
meet  with  such  types  of  animals. 

We  have  now  become  acquainted  with  species  that  seem 
to  be  of  arctic  American  or  Greenland  origin.  A  few 
apparently  travelled  across  from  Europe.  Others  were  partly 
of  southern  extraction  having  advanced  northward  from  the 
United  States,  and  partly  derived  from  a  western  invasion  of 
the  continent.  What  we  want  to  find  out  ne-xt  is  the  geological 
age  of  some  of  these  invasions  into  boreal  America.  The 
writings  on  this  subject  of  the  prominent  biological  authors 
are  largely  biassed  by  the  prevalent  geological  opinions  with 
regard  to  the  nature  of  the  Ice  Age. 

It  is  currently  believed  that  a  climatic  change  towards  the 
end  of  the  Pliocene  Period  caused  ice-masses  to  form  in 
various  Canadian  centres,  so  as  to  produce  continental 
glaciers  of  the  type  of  the  ice-sheet  now  covering  Greenland. 
These  glaciers  are  supposed  to  have  spread  from  at  least  three 
centres  in  Canada,  termed  the  Labradorean,  Keewatin,  and 
Cordilleran.  During  this  time,  viz.,  in  our  most  recent 
geological  age,  the  "  Pleistocene  Period,"  fully  one  half  of 
North  America  is  thus  assumed  to  have  been  gradually  buried 
beneath  these  vast  sheets  of  ice.  Ice  is  believed  to  have  ex- 
tended practically  all  over  the  continent  from  Newfoundland 
in  the  east  to  Vancouver  in  the  west,  and  from  the  Arctic 
Ocean  to  the  present  site  of  the  City  of  St.  Louis.*  Belying 

*  Russell,  I.  0.,  "  North  America,"  p.  315. 
L.A.  D 


84  OKIGIN   OF   LIFE   IN    AMERICA 

on  the  accuracy  of  these  data,  on  which  the  majority  of 
geologists  are  agreed,  biologists  have  endeavoured  to  work 
out  the  past  history  of  the  American  fauna  in  strict  accord- 
ance with  the  facts  these  phenomena  are  thought  to  reveal. 
"  Throughout  the  growth  of  the  great  ice -mass,  and  its  ex- 
tension from  the  north  southward,"  says  Dr.  Merriam,  "  it 
is  clear  that  the  animals  and  plants  that  could  not  keep  pace 
with  its  advance  must  have  perished,  while  the  steady  push- 
ing towards  the  tropics  of  those  that  were  able  to  escape  to 
the  rapidly  narrowing  land  in  that  direction  must  have 
resulted  in  an  overcrowding  of  the  space  available  for  their 
needs  and  a  corresponding  increase  in  the  severity  of  the 
struggle  for  existence."*  Immediately  upon  th,e  close  of  the 
Glacial  Epoch  life  began  to  reclaim  the  regions  from  which 
he  thinks  it  had  so  long  been  shut  out. 

Dr.  Allen's  views  are  very  similar.  "  There  is  evidence," 
he  remarks,  "  that  towards  the  close  of  the  Tertiary,  a  marked 
change  in  the  earth's  climate  took  place,  culminating  in  the 
Glacial  Period,  during  which  the  whole  northern  half  of  the 
northern  hemisphere  became  covered  with  a  heavy  ice-cap, 
lasting  for  possibly  thousands  of  centuries,  and  extending 
its  chilling  influence  nearly  to  the  northern  tropic.  The  rise 
of  the  Glacial  Period  was  of  course  gradual,  and  the  south- 
ward progress  of  the  great  ice- cap  drove  before  it  all  forms 
of  life  capable  of  any  considerable  powers  of  locomotion,  while 
those  unable  thus  to  escape  must  have  perished  from  cold. 
Finally  the  ice  receded  to  its  present  limits  and  the  whole 
north,  under  radically  altered  climatic  conditions,  became 
again  available  for  occupation  by  the  more  or  less  modified 
descendants  of  th,e  pre-Glacial  exiles. "f 

The  bog  plant  societies  so  graphically  described  by  Mr. 
Transeau  probably  existed,  he  thinks,  along  the  whole  ice 
front.  The  bog  and  tundra  types  were  eventually  the  first 
to  push  into  the  barren  ground  left  by  the  retreating  ice.  £ 

Professor  Adams  takes  a  more  independent  attitude.  He 
assumes  that  repeated  glaciation  had  almost  sterilised  the 

*  Merriam,  C.  H.,  "  Life  in  North  America,"  p.  45. 

t  Allen,  J.  A.,  "  Distribution  of  North  American  Birds,"  p.  100. 

|  Transeau,  E.  N.,  "  Distribution  of  Bog  Plant  Societies,"  p.  414. 


FAUNA  OF   WHITE   MOUNTAINS  35 

northern  part  of  the  continent,  still  he  concedes  that  even 
during  the  Glacial  Epoch,  life  of  the  tundra  type  may  have 
flourished  in  Alaska.* 

Hence  it  is  not  unreasonable  to  argue  from  his  point  of 
view  that  life  could  also  have  existed  in  Greenland  at  that 
time,  and  this  opinion  I  endeavoured  to  vindicate  in  the 
last  chapter.  Even  Professor  Adams  does  not  venture  to 
cast  a  doubt  upon  the  correctness  of  the  current  geological 
theories,  and  speaks  of  three  distinct  belts  of  life  in  the 
vicinity  of  the  ice  margin  (p.  56).  The  latter  being  fringed 
to  the  south  by  tundral  biota  (fauna  and  flora),  next  to  which 
came  the  northern  trans -continental  coniferous  forest  belt 
and  its  associated  fauna,  and  finally  the  deciduous  forests. 
All  these  are  assumed  to  have  moved  forward  to  the  north  on 
the  disappearance  of  the  ice. 

That  the  so-called  "  tundral  "  or  what  we  might  call  arctic 
fauna  and  flora  actually  did  advance  far  south  of  their  present 
habitats  can  be  demonstrated  much  more  clearly  than  by  the 
occurrence  of  a  few  stray  fossil  reindeer's  antlers  south  of 
the  area  covered  by  glacial  drift. 

Whether  the  past  southward  migrations  of  the  reindeer 
were  influenced  by  climatic  changes  or  by  other  considera- 
tions, we  cannot  definitely  assert.  Since  we  are  told  that 
there  was  a  refrigeration  of  the  climate  during  the  Glacial 
Epoch,  we  are  apt  to  assume  that  this  lowering  of  the  tem- 
perature drove  the  reindeer  and  other  arctic  species  to  more 
southern  localities.  Tlie  former  occurrence  of  an  animal  of 
such  a  roving  disposition  as  the  reindeer  in  more  southern 
districts  may  have  been  due  to  a  natural  expansion  of  its 
range,  and  this  need  not  imply  a  change  of  temperature. 

The  fauna  and  flora  of  the  White  Mountains  has  been  cited 
as  a  living  testimony  of  a  former  arctic  climate  in  latitudes 
where  temperate  conditions  now  prevail. 

Surrounded  by  an  entirely  alien  assemblage  of  animals  and 
plants  we  find  in  the  White  Mountains  of  New  Hampshire, 
not  far  from  the  city  of  Boston,  an  extraordinary  gathering 
of  species,  many  of  which  are  only  known  elsewhere  in 
Labrador  and  Greenland.  A  thousand  miles  away  from  their 

*  Adams,  Chas.  0.,  "  Dispersal  of  North  American  Biota,"  pp.  55 — 58. 

D    2 


36  OKIGIN   OF   LIFE   IN   AMEKICA 

natural  home,  they  form  in  the  White  Mountains  a  peculiar 
island  colony  on  a  bare  plateau  which  lies  about  5,000  feet 
above  sea-level,  and  out  of  which  project  a  series  of  conical 
peaks.  These  constitute  what  is  known  as  the  Presidential 
Range,  the  highest  being  Mount  Washington  (6,293  feet) 
(Fig.  4).  The  plateau  on  which  this  remarkable  relict  fauna 
and  flora  lives  may  be  reached  by  the  railroad  that  now  takes 
the  traveller  to  the  top  of  Mount  Washington  or  by  following  a 
very  rough  trail  leading  to  it  from  the  Pass  called  "  Crawford's 
Notch  "  through  the  dense  forest.  It  was  the  latter  route  I 
chose  to  gain  the  wind-swept  ridge.  As  we  approach  the 
ridge,  the  fine  spruce,  balsam  and  paper  birches  are  gradually 
replaced  by  diversified  conifers,  which  become  increasingly 
stunted  by  exposure  in  the  more  elevated  parts  of  the  range. 
At  last,  on  emerging  from  the  remnants  of  the  forest,  we 
have  gained  not  only  a  wide  expanse  of  open  country,  but  we 
can  imagine  ourselves  transplanted  all  of  a  sudden  to  the 
Arctic  Regions.  Here  and  there  may  be  gathered  specimens 
of  Rhododendron  lapponicum  and  Salix  phylicifolia,  growing 
among  Arenaria  groenla-ndica,  Phleum  alpinum,  Diapensia 
lapponica,  Campanula  rotundifolia,  Gentiana  nivalis  and 
hosts  of  others,  few  of  which  can  be  studied  elsewhere  nearer 
than  Labrador. 

Moreover,  as  Dr.  Scudder  remarked,  no  State  in  the  Union 
presents  so  striking  an  assemblage  of  animal  life  as  New 
Hampshire,  where  the  White  Mountains  form  so  conspicuous 
a  feature.  Swiftly  running  over  the  bare  rocks  of  the  high 
plateau  we  notice  the  black  spider,  Pardosa  groenlandica, 
which,  though  occurring  also  in  the  Rocky  Mountains,  ,is 
otherwise  confined  to  the  White  Mountains,  Labrador  and 
Greenland.*  The  grasshopper,  Pezzotettix  glacialis,  is,  I 
believe,  peculiar  to  Mount  Washington,  while  another  species, 
Pezzotettix  borealis,  is  a  near  relative  of  the  North  European 
Pezzotettix  frigida.  Fluttering  among  the  arctic  vegetation, 
we  notice  the  butterfly  Oeneis  semidea,  which  has  never  been 
taken  nearer  than  Labrador,  while  the  moths  Dasychira  rossii, 
Arctia  quenselii  and  Anarta  melanopa,  are  all  well-known 

*  Chamberlin,  E.    V.,    "  Eevision  of    North  American  Lycosidae," 
p.  200. 


FIG.  4.— Map  showing  the  outlines  of  the  White  Mountain  Plateau  (shaded)  and 
Mount  Washington  Range  (black),  with  an  inset  Map  of  North  America, 
indicating  the  position  of  the  White  Mountains  (in  the  centre  of  small  circle). 

[To  face  p.  36. 


OBIGIN   OF  WHITE   MOUNTAIN   FAUNA         37 

arctic  species  occurring  on  th<e  White  Mountain  plateau.* 
Among  the  beetles,  too,  and  other  groups  of  invertebrates, 
there  are  many  arctic  forms,  showing  clearly  the  intimate 
relationship  that  exists  between  the  faunas  of  the  White 
Mountains  and  Labrador. f 

Even  among  mammals  we  have  some  most  interesting 
boreal  representatives,  the  White  Mountain  lemming- vole 
(Synaptomys  sphagnicola)  being  peculiar  to  this  region.  J  In 
alluding  to  the  mammalian  fauna  of  Labrador  I  specially 
dealt  with  this  genus,  and  expressed  the  belief  in  its  arctic 
origin  and  subsequent  southward  dispersal  (p.  28). 

If  merely  a  few  arctic  plants  and  insects  inhabited  this  re- 
markable plateau,  the  argument  might  be  permissible  that 
they  had  been  carried  southward  by  wind  currents  from  their 
northern  home  at  great  intervals  of  time  and  had  successfully 
established  themselves  in  this  manner  on  the  White  Moun- 
tains, because  the  latter  proved  to  be  uninhabitable  by  the 
fauna  and  flora  of  the  surrounding  country.  No  one,  however, 
who  has  seriously  studied  this  congregation  of  animals  and 
plants  as  a  whole,  can  for  a  moment  entertain  such  an  idea. 
We  must  therefore  take  for  granted  that  a  fauna  and  flora 
similar  to  that  now  existing  in  Greenland,  Labrador  and  on 
the  White  Mountains  once  extended  over  a  large  portion  of 
Canada  and  at  any  rate  the  north-eastern  United  States.  The 
problem  to  be  solved  is,  what  were  the  circumstances  which 
led  those  animals  and  plants  to  extend  their  range  so  much 
southwards  ?  The  prevalent  theories  regarding  these  move- 
ments have  already  been  referred  to.  They  are  simple  enough. 
Similar  ones  have  been  current  in  Europe  for  many  years 
past.  I  shall  quote  Professor  Adams  §  again,  as  his  views 
seem  to  me  to  express  those  generally  entertained  on 
this  subject.  After  an  allusion  to  the  final  northward  retreat 
of  the  ice  which  he  supposed  to  have  crept  down  from  the 
north  "  grinding  to  pieces  everything  beneath  its  awful 

*  Scudder,   S.    H.,    "  Distribution   of  Insects   in    Now  Hampshire," 

pp.  331—341. 

f  Gardiner,  F.,  "  Coleoptera  of  the  White  Mountains." 

|  Miller,  GK,  "  Mammals  of  New  Hampshire  Mountains." 

§   Adams,    Charles   0.,  "  Post-glacial  Origin   of    the  life  of  North  - 

Eastern  United  States,"  p.  309. 


38  OKIGIN   OF   LIFE   IN   AMERICA 

weight,"  it  once  more  permitted  life  from  the  south  to  move 
into  the  newly  opened  territory.  The  first  wave  of  life,  he 
thinks,  which  became  dispersed  over  the  glaciated  region,  as  I 
have  already  mentioned  above,  was  the  barren-ground  fauna 
and  flora,  the  types  of  the  far  north.  "  Hardly  a  trace," 
he  continues,  "  now  remains  in  the  eastern  United  States  of 
this  pioneer  class,  and  this  class  is  now  restricted  to  very 
limited  areas  or  mountain  top  '  islands,'  as  in  the  White 
Mountains.  The  present  distribution  of  these  arctic-alpine 
'  islands  '  brings  up  a  number  of  very  interesting  points.  How 
is  it  that  these  alpine  plants  and  animals  are  now  found  so  far 
south  and  only  upon  high  mountain  peaks  ?  This  question 
could  not  be  rationally  explained  until  the  influence  of  the  Ice 
Age  upon  life  became  recognised,  and  would,  indeed,  be  a 
difficult  one  to  answer  if  we  did  not  take  into  consideration 
past  conditions  of  climate  and  topography.  We  must  recall 
that  the  arctic  conditions  which  now  occur  outside  of  the  arctic 
regions  only  on  high  mountain  tops  at  that  time  extended  to 
the  very  base  of  the  mountains,  and  as  the  ice  retreated  to  the 
north  this  cold  zone  gradually  moved  up  the  sides  of  the 
mountains  carrying  with  it  a  characteristic  flora  and  fauna. 
Thus  with  the  retreat  of  the  ice  the  first  wave  of  life  had 
two  evident  possibilities  before  it:  first,  to  follow  the  ice 
north,  or  to  follow  the  cold  zone  up  the  mountains.  By  this 
means  small  colonies  of  arctic  plants  and  animals  became 
separated  from  the  main  body  of  forms,  and  thus  became 
alpine.  To  be  sure,  this  segregation  could  only  occur  where 
the  mountain  peaks  are  isolated.  If  the  mountains  had  been 
of  sufficient  height  and  had  extended  far  to  the  north,  a  high- 
way would  have  been  retained  to  the  original  stock,  and  thus 
the  distribution  would  not  have  become  discontinuous.  From 
the  above  interpretation  it  seems  fair  to  conclude  that  the 
arctic  forms  which  now  occur  at  alpine  heights  are  relicts  of 
the  former  widespread  glacial  fauna  and  flora,  whose  dis- 
tribution has  become  discontinuous  by  a  change  of  climate." 
Very  similar  ideas  were  held  by  Mr.  Grote.*  He  thought 
the  White  Mountain  butterfly  (Oeneis  semidea)  was  pushed 
southwards  by  the  advance  of  the  great  northern  ice-sheet. 

*  Grote,  A.  E.,  "  Effect  of  Glacial  Epoch,"  p.  441. 


OBIGIN   OF   WHITE   MOUNTAIN   FAUNA         89 

On  the  decline  of  the  ice-sheet  the  butterflies  turned  north- 
ward, again  returning  to  their  native  home.  Some  of  the 
specimens  strayed  by  the  way  and  were  destined  to  planlt 
colonies  apart  from  their  companions  as,  for  example,  on  the 
White  Mountains. 

Botanists  entertain  analogous  views.  Dr.  Harshberger  * 
argues  that  the  tundra  vegetation  and  other  arctic  species 
of  plants  occupied  during  the  Glacial  Epoch  the  southern 
margin  of  the  great  ice-sheet,  and  that  when  most  of  them 
migrated  north,  on  the  disappearance  of  the  ice,  some  re- 
mained behind  to  form  the  vegetation  of  sphagnum  bogs  and 
alpine  summits  of  the  higher  mountains. 

If  these  theories  are  correct,  the  Asiatic  invasion  and  the 
much  more  insignificant  one  from  Europe,  of  which  Helix 
hortensis  is  one  of  the  most  striking  representatives  (p.  13), 
should  both  be  more  recent  than  the  flora  and  fauna  of  the 
White  Mountains,  for  the  former  have  n6t  penetrated  beyond 
the  lower  slopes  of  these  mountains. 

Helix  hortensis  does  not  occcur  nearer  the  White  Mountains 
than  Portland  in  Maine,  which  is  fully  seventy  miles  to  the 
east.  I  have  traced  Oniscus  asellus,  a  wood-louse  probably 
belonging  to  the  same  group,  as  far  as  the  base  of  the  White 
Mountains.  The  earth-worm,  Lumbricus  castaneus,  which 
seems  to  have  spread  from  wntinental  Europe  to  the  Faroes 
and  Iceland,  reappearing  on  the  other  side  of  the  Atlantic 
in  Canada  and  New  England,  may  be  a  member  of  the  same 
dispersal.  At  any  rate,  I  feel  sure  there  are  a  great  many 
more  of  such  species  that  have  not  spread  to  the  higher  parts 
of  the  White  Mountains,  and  therefore  proclaim  themselves  as 
more  recent  immigrants  than  those  which  are  now  in  posses- 
sion of  the  high  plateau  referred  to.  The  latter  are  likewise 
clearly  older  than  the  Asiatic  immigrants,  which  will  l)e  more 
fully  described  later  on. 

But  since  Helix  hortensis  occurs  in  the  lower  Pleistocene 
clays  of  Maine,  it,  as  well  as  the  whole  group  of  European 
immigrants,  are  pre-Glacial  in  age,  and  in  this  opinion  I 
concur  with  several  of  the  authorities  who  have  discussed, 
this  problem  (p.  14).  The  members  of  this  group  arrived 

*  Harshberger,  John  W.,  "  North  American  Plant  Dispersal,"  p.  2. 


40  OEIGIN   OF   LIFE   IN   AMERICA 

in  America  before  the  time  when  the  glacial  drift  was  de- 
posited, or,  in  other  words,  when  the  northern  ice -sheets  were 
•supposed  to  have  advanced  to  their  southern  limits.  The 
glacial  drift,  I  may  mention  again,  is  the  mantle  of  clay,  sand 
and  boulders  believed  to  have  been  left  by  the  ice  as  it 
retreated  northward.  Whether  this  drift  or  boulder  clay  really 
is  the  product  of  immense  glaciers,  or  whether  it  was  deposited 
in  the  sea  by  floating  icebergs,  it  is  evident  that  wherever  the 
country  is  covered  by  it  the  pre-existing  fauna  and  flora  must 
have  been  destroyed.  The  evidence  seems  to  me  all  in 
favour  of  destruction  rather  than  emigration. 

The  idea  of  a  gradual  southward  withdrawal  of  the  fauna 
and  flora,  that  they  fled  like  a  conquered  army  before  an  ad- 
vancing foe,  sounds  very  plausible,  but  is  there  any  foundation 
for  such  a  belief  ? 

No  evidence  can  be  adduced  from  fossil  specimens  that 
any  members  of  what  I  have  called  the  European  invasion 
ever  penetrated  southward  of  the  limits  of  the  drift  in  North 
America.  They  do  not  seem  to  have  been  pushed  south  in  front 
of  the  advancing  masses  of  northern  ice.  Theoretically,  they 
ought  to  have  survived  the  Ice  Age  somewhere  in  south-eastern 
North  America.  If  they  did,  they  must  subsequently  have 
reoccupied  the  very  parts,  viz.,  Labrador,  Newfoundland  and 
the  coast  of  New  England,  where  they  originally  set  .foot 
on  American  soil  after  completing  their  travels  across  the 
North  Atlantic  land  bridge.  But  is  it  possible  that  they 
quitted  the  south-eastern  States  without  leaving  a  trace  of 
their  former  presence  there  ?  As  Dr.  Harshberger  *  points 
out,  not  a  single  species  of  thirty-four  plants  characteristic 
of  the  area  just  south  of  the  glacial  drift  deposits,  is  a  native 
of  Europe.  On  the  other  hand,  of  the  plants  growing  on 
th,e  drift  itself,  about  one-third  are  common  to  northern 
Europe  and  America.  All  the  available  evidence,  therefore, 
points  to  a  survival  of  the  European  element  within  the 
glaciated  area. 

Could  any 'islands  have  existed  in  the  midst  of  this  glaciated 
area,  where  this  assemblage  of  European  plants  and  animals 

*  Harshberger,  J.  W.,  "  Comparative  Age  of  Floristic  Elements," 
p.  606. 


NORTH-EASTERN   RELICT  COLONIES  41 

might  have  survived  the  Ice  Age,  without  being  affected  by 
the  Ice-sheets  ? 

Labrador  was  one  of  the  areas  which  was  believed  to  have 
had  an  independent  centre  of  glaciation,  yet  Professor  Daly,* 
after  inaking  a  special  study  of  the  geology  of  Labrador, 
remarked  "  nothing  is  more  striking  in  the  glacial  geology  of 
the  southern  part  of  the  coastal  belt  than  the  almost  com- 
plete absence  of  drift  deposits."  In  the  Torngat  Mountains  of 
Labrador  no  signs  of  glaciation  were  noticeable  above  2,000 
feet.  That  there  were  considerable  tracts  of  Labrador  which 
were  free  from  ice  must  be  evident,  and  I  presume  the  Euro- 
pean plant  and  animal  migrants  survived  the  Glacial  Epoch 
there  and  also  further  south.  The  island  of  Newfoundland 
seems  to  have  had  quite  a  separate  area  of  glaciation,  and  the 
same  was  probably  true  of  Nova  Scotia,  according  to  Pro- 
fessors Chamberlin  and  Salisbury. f 

The  two  countries  of  Labrador  and  Newfoundland  have 
many  species  of  animals  and  plants  in  common,  and  in  both 
no  doubt  a  large  part  of  the  pre-existing  fauna  and  flora  sur- 
vived the  Glacial  Epoch.  I  have  urged  in  the  last  chapter 
(p.  14)  that  the  land  probably  stood  at  a  much  higher  level 
towards  the  beginning  of  the  Pleistocene  Period  than  at  pre- 
sent, the  whole  of  the  Bank  of  Newfoundland,  and  southward 
as  far  as  Cape  Cod,  being  raised  high  above  sea-level.  While 
I  claim  that  the  remainder  of  boreal  North  America  has  sub- 
sequently become  largely  submerged,  these  eastern  tracts  are 
likely  to  have  remained  above  water,  thus  forming  an  asylum 
for  the  survival  of  the  arctic  and  Old  World  fauna  and  flora. 
This  opinion  is  confirmed  by  Professor  Upham's  J  remark 
that  the  elevation  of  the  fossilif erous  marine  beds  lying  on  the 
glacial  drift  increases  as  we  proceed  north,-westward  from 
Boston,  that  is  to  say,  inland,  while  along  the  lower  St. 
Lawrence  it  decreases  again,  so  that  in  Nova  Scotia  actually 
on  the  sea-coast  marine  deposits  are  wanting. 

The  current  geological  theories  of  the  Ice  Age  or  Glacial 

*  Daly,  E.  A.,  "  Geology  of  Labrador,"  pp.  245—251. 
t  Chamberlin,    T.  0.,  and  E.    D.    Salisbury,    "  Geology,"   Vol.  III., 
p.  336. 

{  Upham,  Warren,  "  Marine  Shells  near  Boston,"  p.  140. 


42  ORIGIN   OF   LIFE    IN   AMERICA 

Epoch  do  not  seem  to  me  to  harmonise  at  all  with  the  geo- 
graphical distribution  of  animals  and  plants.  If  we  assume 
that  an  arctic  climate  prevailed  at  that  time  all  over  Canada 
and  the  northern  United  States,  we  are  faced  by  numerous 
difficulties.  The  biological  evidence  favours  the  view  that  the 
climate  in  boreal  North  America,  though  much  more  humid 
than  at  present,  so  that  it  led  to  extensive  glaciation  on  all 
higher  mountain  ranges,  was  not  arctic  but  temperate,  and 
that  in  many  parts  within  the  so-called  glaciated  area  there 
existed  islands  where  life  was  abundant  and  survived  to  the 
present  day. 

Let  us  return  to  the  animals  and  plants  inhabiting  the 
White  Mountains.  Their  relationship  is  almost  altogether 
with  Lapland  and  Greenland,  and  yet  that  affinity  has  clearly 
been  brought  about  at  a  much  earlier  date  than  that  of  the 
arrival  of  the  European  element  in  North  America. 

During  the  Pliocene  Period  movements  seem  to  have  taken 
place  resulting  in  an  increased  height  of  land.  This  need  not 
necessarily  have  affected  the  whole  of  North  America.  It  was 
probably  more  or  less  confined  to  the  north-eastern  and  north- 
western parts.  While  the  closing  of  the  North  Atlantic  left 
the  coastal  districts  open  to  the  beneficial  influence  of  the 
Gulf  Stream,  the  temperate  fauna  and  flora  must  have  gradu- 
ally disappeared  from  the  more  inland  boreal  parts  of  the  con- 
tinent, thus  leaving  room  for  the  expansion  of  the  arctic 
animals  and  plants  in  various  directions.  It  was  during  the 
Pliocene  Period,  I  think,  or  earlier,  and,  at  any  rate,  long 
before  the  commencement  of  the  Glacial  Epoch,  that  the 
animals  and  plants  from  Labrador  thus  found  their  way  south- 
ward to  the  White  Mountains.  However,  1  shall  bring  forward 
further  evidence  later  on  which  will  throw  additional  light 
on  the  problems  I  have  discussed. 

The  theory  that  the  animals  and  plants  were  driven  south 
of  the  ice  foot  or  southern  margin  of  the  supposed  great 
ice -sheet  ought  to  be  supported  by  biological  evidence. 

Theoretically  it  is  assumed  that  the  barren-ground  or  arctic 
fauna  and  flora  lived  close  to  this  margin,  as  already  stated, 
and  the  temperate  forms  further  south.  The  only  fossil  evi- 
dences we  possess  of  arctic  animals  having  actually  lived  south 
of  the  ice-sheet,  or,  as  we  might  say,  south  of  the  limits  of 


EFFECTS   OF   ICE   AGE   ON   FAUNA  43 

the  drift,  are  rather  problematical.  Most,  if  not  all,  the  occur- 
rences of  reindeer  and  musk  ox  bones  lie  within  the  drift  area. 
As  already  mentioned,  animal  remains  have  been  met  with  in 
caves  and  other  deposits,  close  to  the  limits  of  the  drift,  and 
supposed  to  belong  to  the  Pleistocene  Period,  which  seem  to 
indicate  a  climate  somewhat  milder  than  the  present  one. 

The  most  noted  Pleistocene  fossiliferous  strata  within  the 
drift  area  lie  in  Canada,  and  these  contain  largely  the  remains 
of  plants.  Since  the  first  place  as  tests  of  climate  has  gene- 
rally been  assigned  to  plants,*  their  testimony  will  be  of 
particular  value  in  our  present  enquiries.  These  deposits  have 
been  principally  studied  by  Professors  Coleman'f  and  Pen- 
hallow.  J  Some  are  in  the- neighbourhood  of  Toronto  near  the 
shores  of  Lake  Ontario,  others  further  west  near  the  Moose 
and  Albany  Kivers,  both  of  which  empty  their  waters  into 
Hudson  Bay. 

In  dealing  with  the  beds  in  the  neighbourhood  of  Toronto, 
Professor  Coleman  reports  that  those  of  Scarboro'  Heights 
contain  mosses,  diatoms,  a  few  fresh-water  shells  and  a  con- 
siderable number  of  elytra  of  beetles.  According  to  Dr. 
Scudder  the  latter,  numbering  twenty-nine  species,  are  all 
extinct,  and  related  to  species  occurring  in  Lake  Superior  and 
Hudson  Bay  regions,  the  fauna  having  a  boreal  aspect.  The 
fossils  from  the  Don  Eiver  deposits  were  found  to  be  sur- 
prisingly different.  They  seemed  to  point  to  a  climate  as 
warm  as  that  of  Toronto,  if  not  much  warmer,  while  the  forest 
trees  suggest  a  temperature  far  from  glacial.  Not  a  trace  of 
an  arctic  fauna  or  flora  could  be  discovered.  It  was  con- 
cluded, therefore,  by  Professor  Coleman  that  both  these  series 
of  beds  were  inter-glacial,  that  is  to  say,  laid  down  during  the 
mild  phases  which  are  supposed  to  have  separated  the  in- 
tensely arctic  ones  from  one  another. 

The  plant  remains  from  the  other  deposits  were  like  those 
of  Scarboro'  Heights  and  Montreal.  They  were  essentially  of 
the  same  character  representing  a  vegetation  similar  to  that 
of  our  own  time,  or  perhaps  even  a  little  more  severe. 


*  Seward,  A.  C.,  "Fossil  Plants  as  Tests  of  Climate,"  p.  10. 

t  Coleman,  A.  P.,  "  Glacial  and  Inter-glacial  Deposits,"  pp.  625 — 640. 

I  Penhallow,  I).  P.,  "  Pleistocene  Flora  of  Canada,"  p.  77» 


44  OKIGIN   OF   LIFE  IN   AMERICA 

Four  years  later  a  valuable  report  on  the  Pleistocene  fauna 
and  flora  of  Canada  was  read  at  the  British  Association  Meet- 
ing at  Bradford  by  a  committee  which  had  been  appointed  to 
investigate  the  subject.  Of  this  committee,  Professor  Cole- 
man  and  Professor  Penhallow  were  members,  as  well  as 
Sir  William  Dawson.*  The  number  of  beetles  brought  to  light 
from  the  Scarboro'  Heights  had  now  increased  to  seventy-two 
species,  of  which  seventy  were  pronounced  by  Dr.  Scudder  to 
be  extinct.  The  new  species  confirmed  Dr.  Scudder  in  the 
opinion,  previously  expressed,  that  on  the  whole  the  fauna 
has  a  boreal  aspect,  though  by  no  means  so  decidedly  boreal 
as  one  would  anticipate. 

No  less  than  eighty-three  species  of  plants  were  studied 
from  eighteen  different  localities,  one  of  the  plants,  viz.,  Acer 
pleistocenicum,  being  extinct.  The  abundant  occurrence  of 
some  species,  such  as  the  Osage  orange  (Maclura  aurantiaca), 
the  paw-paw  (Asimina  triloba)  and  others,  point  to  the  pre- 
valence of  a  much  warmer  climate  than  now  prevails.  On 
the  other  hand,  the  equally  abundant  occurrence  of  boreal 
types  at  Scarboro'  Heights  suggests  the  existence  of  a  cooler 
climate  at  the  time  these  deposits  were  laid  down. 

Once  more,  in  1907,  Professor  Penhlallow  f  dwelt  upon  the 
results  of  his  researches  on  the  plant  remains  of  the  Don 
River  beds,  urging  that  the  same  flora  must  have  characterised 
the  entire  region  between  Virginia  and  Ontario  in  Pleistocene 
times,  whilst  a  much  warmer  climate  than  at  present  pre- 
vailed. 

If  similar  evidence  were  brought  to  light  from  any  other 
deposit  than  the  Pleistocene,  there  can  be  no  doubt  as  to  the 
conclusions  that  would  be  drawn  from  it.  The  climate  in 
boreal  North  America  during  the  Pleistocene  Period,  as  re- 
vealed by  the  plant  and  animal  remains,  must  have  been  on  the 
whole  a  temperate  one.  Yet  geologists  maintain,  in  the  face 
of  this  testimony,  that  all  these  plant  and  animal  remains  only 
represent  the  so-called  interglacial  phase  of  the  Glacial 
Epoch,  during  which  the  climate  was  supposed  to  have  been 
temperate  or  mild.  The  other  phase  of  the  Ice  Age,  they 

*  Dawson,  J.  W.,  D.  P.  Penhallow  and  others,  "Canadian  Pleistocene 
Fauna  and  Flora,"  p.  334—338. 

t  Penhallow,  D.  P.,  "Pleistocene  Flora  of  Canada,"  pp.  443-450. 


ON   INTERGLACIAL   EPOCHS  45 

f 

argue,  has  left  no  traces  of  animal  or  plant  life  in  all  the 
numerous  deposits  which  have  been  examined. 

The  whole  conception  of  these  interglacial  phases  of  the 
Glacial  Epoch  has  given  rise  to  a  good  deal  of  animated 
discussion.  Professors  Chamberlin  and  Salisbury  have 
adopted  Professor  James  Geikie's  view  that  there  were 
six  great  advances  and  retreats  of  the  ice -sheets,  sepa- 
rated by  five  interglacial  intervals,  during  which  a  mild 
climate  prevailed.  But  the  evidences  for  these  alternate 
advances  and  /retreats  of  the  glaciers  are  "by  no  means  ad- 
mitted as  valid  by  all  geologists.  Some  maintain  that  there 
were  only  three  such  great  advances  and  retreats.  Others 
admit  only  two  of  them.  Some  authorities  disbelieve  alto- 
gether in  mild  interglacial  phases,  and  admit  only  one  ad- 
vance followed  by  a  gradual  retreat  of  the  ice.  Even  after 
studying  the  Toronto  clays,  which  Mr.  Lamplugh  *  acknow- 
ledges impressed  him  strongly  as  affording  the  kind  of  evi- 
dence which  he  has  sought  in  vain  in  Britain,  he  is  still  of 
opinion,  as  expressed  in  his  address  to  "the  Geological  Section 
of  the  British  Association,  that  there  is  no  proof  of  mild  inter- 
glacial epochs,  nor  even  of  one  such  epoch. 

My  own  conclusions  as  to  the  nature  of  the  Glacial  Epoch, 
and  the  causes  that  produced  the  glacial  clays,  being  almost 
entirely  based  on  the  evidence  derived  from  the  past  and  pre- 
sent fauna  and  flora,  I  have  no  hesitation  in  agreeing  with 
Mr.  Larnplugh's  views.  There  is  no  biological  evidence  in 
North  America  in  favour  of  one  or  more  interglacial  phases. 
Everything  moreover  points  to  the  fact  that  during  the  so- 
called  Glacial  Epoch  there  was  no  diminution  of  temperature, 
or  if  so  only  a  very  partial  one,  although  the  higher  mountain 
ranges  were  covered  by  glaciers.  In  many  parts  of  North 
America  there  was  probably  a  higher  temperature  during  the 
Ice  Age  than  obtains  at  present.  The  first  to  advocate  the 
idea  of  a  higher  mean  temperature  being  compatible  with  a 
greater  extension  of  glaciers  was,  I  think,  Professor  Lecoq.*j~ 

Much  more  recently  a  similar  theory  was  very  ably  main- 

*  Lamplugh,  G.  W. ,  "  On  British  Drifts  and  the  Inter-Glacial  Problem," 
p.  26. 

t  Lecoq,  H.,  "  Des  Glaciers  et  des  Climats." 


46  ORIGIN   OF   LIFE   IN   AMERICA 

tained  by  Professor  Whjtney.*  and  was  supported  by  weighty 
arguments,  while  Sir  Henry  Howorth  f  has  contributed  addi- 
tional testimony  in  favour  of  a  mild  climate  having  prevailed 
during  the  so-called  Glacial  Epoch  or  Ice  Age. 

That  extensive  glaciers  existed  during  that  Epoch  in 
western  Europe  and  north-eastern  North  America  is  pri- 
marily due  to  the  closing  of  the  North  Atlantic.  This  pro- 
duced a  rise  of  temperature  in  the  Atlantic  Ocean  and  intense 
precipitation  over  western  Europe,  particularly  Scandinavia, 
and  also  .over  north-eastern  America,  especially  Labrador. 
As  Professor  Whitney  observes,  the  regions  mentioned  are  the 
only  two  in  the  world  in  which  the  topographical  and  climatic 
conditions  seem  to  have  been  considerably  different  during  the 
Glacial  Epoch  from  what  they  are  at  present.  The  prevail- 
ing opinion,  however,  among  geologists  is,  that  not  only  was 
there  -a,  centre  of  glaciation  in  Labrador,  but  also  in  the 
Keewatin  district  to  the  west  of  Hudson  Bay.  The  latter  being 
a  perfectly  flat  region,  without  even  a  suggestion  of  a  moun- 
tainous nucleus,  constitutes, indeed,  as  Professors  Chamberlin 
and  Salisbury  J  acknowledge,  one  of  the  most  marvellous  fea- 
tures in  ice  dispersion.  All  our  notions  as  to  the  behaviour  of 
glaciers  are  derived  from  careful  .observations  on  existing  ones. 
But  nowhere  on  earth  can  a  glacder  be  seen  which,  having 
originated  on  level  land  and  developed  quite  independently  of 
any  adjacent  higher  region,  proceeds  to  invade  the  neigh- 
bouring areas.  Hence  a  biologist  may  be  excused  for  express- 
ing some  hesitation  in  accepting  so  extraordinary  an  hypo- 
thesis in  spite  of  the  fa-ct  that  we  are  assured  that  the  days 
of  reasonable  doubt  as  to  the  former  existence  of  these  almost 
inconceivably  large  ice-fields  are  past. 

To  attempt  even  to  discuss  all  the  various  lines  of  evi- 
dence which  have  led  to  the  almost  general  acceptance  of  the 
land-ice  theory,  as  understood  at  the  present  day,  would  be 
impossible  in  a  work  of  this  nature .  I  only  wish  to  bring 
forward  some  of  the  chief  reasons  which  have  prevailed  upon 
me  to  reject  this  theory.  I  c?an  scarcely  venture  to  hope  that 

*  Whitney,  J.  D.,  "  Climatic  Changes,"  p.  321. 

t  Howorth,  H.  H.,  "Ice  or  Water,"  Vol.  II.,  p.  492. 

J  Chamberlin,  T,  C,,  and  B,  D,  Salisbury,  "  Geology,"  III.,  p.  332. 


FORAMINIFERA   IN   THE    DRIFT  47 

my  criticisms  will  be  readily  accepted,  yet  they  may  possibly 
help  in  clearing  up  some  points  which  hitherto  could  not  be 
satisfactorily  elucidated  by  other  methods.  The  vast  drift 
deposits  which  shroud  the  country  like  a  great  mantle  of  clay, 
sand  and  stones,  frequently  contain  the  remains  of  the  ex- 
clusively marine  group  of  foraminifera.  Mr.  Joseph  Wright, 
a  well-known  European  authority,  has  shown  that  the  species 
of  foraminifera  have  a  very  wide  distribution  in  European 
boulder-clays.  And  it  appears,  on  the  authority  of  Sir  Henry 
Howorth,*  that  Mr.  Wright  has  likewise  identified  foramini- 
fera from  American  glacial  clays.  Samples  were  .submitted 
to  him  by  the  late  Dr.  G.  Dawson  from  Saskatchewan 
River,  1,850  feet  above  sea-level,  from  Selkirk  in  Manitoba, 
and  from  Ottawa.  The  sample  from  Saskatchewan  contained 
specimens  of  foraminifera  referable  to  recent  species,  one 
of  which  (Nonionina  depressula)  is  also  common  in  European 
boulder-clays. 

It  is  quite  possible  that  foraminifera  may  be  found  in  many 
other  localities  in  the  same  clays  ;  indeed,  Sir  Henry  Howorth 
mentions  that  Sir  William  Dawson  had  found  them  generally 
diffused  in  the  Pleistocene  clays  of  Canada.  This  fact,  there- 
fore, tends  to  support  Colonel  Feilden's  f  contention  that  all 
the  glacial  deposits  which  he  had  examined  in  Arctic  and  Polar 
lands,  with  the  exception  of  terminal  moraines  now  forming 
above  sea-level,  are  glacio-marine  beds. 

Supposing  the  waters  of  the  Arctic  Ocean  had  risen,  per- 
haps in  consequence  of  the  closing  of  the  Atlantic  Ocean, 
and  had  poured  into  Hudson  Bay,  overflowing  its  banks, 
and  had  then  crossed  the  low-lying  watershed  separating 
this  northern  region  from  the  depressions  of  the  Great  Lakes, 
the  latter  would  soon  have  been  filled  with  brackish  water, 
killing  or  driving  away  many  of  those  forms  of  life  that  were 
unable  to  adapt  themselves  to  this  change  of  conditions.  I 
presume,  of  course,  that  troughs,  not  necessarily  like  the 
lakes  now  existing,  already  occupied  the  same  region  in  pre- 
Glacial  times.  Such  an  hypothesis  of  this  area  having  been 
invaded  by  the  sea  in  Pleistocene  times  is  supported  by  some 

*  Howorth,  H.  H.,  "Ice  or  Water,"  Vol.  II.,  p.  216. 

t  Feilden,  H.  W.,  "  Glacial  Geology  of  Arctic  Europe,"  p.  57. 


48  OKIGIN   OF   LIFE   IN   AMERICA 

biological  evidence,  though  it  Is  usually  argued  that  the  ocean 
crept  inland  through  the  St.  Lawrence  or  Hudson  Eiver 
Valley. 

Fifty  years  have  elapsed  since  Professor  Loven  *  first  drew 
attention  to  the  presence  of  several  crustaceans,  allied  to 
marine  forms,  in  Swedish  lakes,  and  endeavoured  to  prove  that 
the  latter  -must  have  been  covered  by  the  sea  in  recent  geo- 
logical times.  One  of  these  crustaceans  is  the  fresh-water 
shrimp  Mysis  relicta,  closely  related  to  the  common  Arctic 
marine  form  Mysis  oculata.  Since  the  latter  does  not  occur  in 
the  Baltic,  the  theory  that  Mysis  relicta  is  a  recent  immigrant 
from  that  sea  is  untenable.  It  seems  much  more  probable 
that  it  gradually  developed  from  its  marine  relative  Mysis 
oculata,  when  the  Arctic  Ocean  covered  the  lowlands  of 
northern  Eussia,  Sweden  and  northern  Germany.  This  view 
is  confirmed  by  the  fact  that  Mysis  relicta  has  now  been  dis- 
covered, along  with  other  marine  organisms,  in  several  lakes, 
all  of  which  are  situated  within  the  area  covered  by  the  north 
European  drift.  I  have  also  alluded  to  its  occurrence  in 
Lough  Neagh  in  Ireland.f 

Now  it  is  of  great  interest  that  this  small  freso.-wa.ter 
shrimp  Mysis  relicta,  which  is  so  closely  related  to  a  marine 
species,  should  also  occur  abundantly  in  Lakes  Superior  and 
Michigan.  First  discovered  in  the  stomach  of  a  Coregonus 
taken  in  Lake  Michigan  by  Dr.  Hoy,  it  was  subsequently  met 
with  by  Dr.  Stimpson,J  living  in  about  fifty  fathoms  of  water 
in  the  same  lake.  It  has  since  been  noticed  in  Lake  Superior 
by  Messrs.  Smith  and  Verrill,  but  in  no  other  of  the  Canadian 
lakes.  This  is  in  so  far  significant,  as  neither  of  these  two 
lakes  are  supposed  to  have  been  invaded  by  the  sea  in  Glacial 
and  post-Glacial  times.  All  that  geologists  acknowledge  is 
that  the  sea  crept  up  the  Hudson  Eiver  and  the  St.  Lawrence, 
as  far  as  the  western  end  of  Lake  Ontario.  The  latter  and 
Lake  Champlain  had  then  a  marine  fauna,  and  it  is  there 
that  we  should  expect  Mysis  relicta  to  occnr. 

But    besides    this    fresh-water    shrimp,    another     small 

*  Loven,  S.,  "  Tiber  einige  Crustaceen." 

t  Scharff,  E.  F.,  "European  Animals,"  p.  155. 

J  Stimpson,  A.,  "  Fauna  of  Lake  Michigan,"  p.  403. 


RELICT  FAUNA  OF  GREAT  LAKES     49 

crustacean,  called  Pontoporeia  hoyi,  allied  to  a  marine  form, 
inhabits  the  Lakes  Michigan  and  Superior,  while  in  the 
former  still  another  marine  form  (Pontoporeia  filicornis)  and  a 
remarkable  fish  called  Triglopsis  thompsoni  have  been  met  with. 
Professor  Peschel  first  applied  the  term  "  relict  lakes  "  * 
to  lakes  like  those  referred  to,  because  they  contain  the 
relicts  of  a  former  sea,  and  the  word  has  since  been  largely 
adopted  in  the  sense  in  which  it  was  first  proposed.  Never- 
theless, some  authorities,  notably  Professor  Credner,f  who 
treated  the  subject  most  exhaustively,  maintain  that  these 
so-called  relict  animals  have  either  immigrated  to  the  fresh- 
water lakes  directly  from  the  sea,  or  have  been  transportedi 
from  their  marine  habitat  by  accidental  means.  He  notes 
with  surprise  the  absence  from  all  the  so-called  relict  lakes 
of  marine  mollusks  or  species  allied  to  such,  contending  that 
some  of  them  ought  to  be  found  in  these  lakes,  if  the  latter 
had  ever  been  covered  by  the  sea.  Professor  Credner's  argu- 
ments against  the  relict  nature  of  such  lakes  as  Superior  and 
Michigan,  seem  at  first  sight  very  convincing.  But  zoo- 
logists are  now  well  acquainted  with1  the  fact  that  all  marine 
mollusks  have  free-swimming  larvae.  These  being  altogether 
a  prey  to  currents  would  infallibly  be  swept  into  the  sea  if 
placed  into  running  fresh  water.  Thus  the  parent  marine 
mollusks  would  be  unable  to  propagate  their  kind  in  fresh 
water  even  if  they  could  adapt  themselves  to  it.  This  circum- 
stance seems  to  account  in  a  satisfactory  manner  for  the 
absence  of  marine  mollusks  from  relict  lakes.  Quite  apart 
from  this  objection  to  the  relict  theory,  Professor  Credner's 
contention  of  an.  active  migration  of  marine  organisms  to 
fresh  water  is  particularly  inapplicable  in  the  case  we  have 
been  considering,  because  none  of  the  "  relict  species " 
alluded  to  occur  in  the  lower  lake  of  Ontario,  which,  moreover, 
is  separated  from  the  upper  lakes  by  the  impassable  Niagara 
waterfall.  It  is  of  interest  also  to  note  that  the  only  other 
locality  in  which  the  fish  Triglopsis  thompsoni  has  been 
taken,  besides  that  of  the  Great  Lakes,  is  in  tidal  pools  on  the 
west  coast  of  Hudson  Bay. 

*  Peschel,  O.,  "  Vergleichende  Erdkunde,"  p.  167. 
t  Oredner,  E.,  "  Eeliktenseen,"  I.,  p.  105. 

L.A.  B 


50  ORIGIN  OF   LIFE   IN   AMERICA 

Other  species  of  fishes  related  to  marine  forms  live  in  the 
Great  Lakes.  But  we  need  not  suppose  that  typical  fresh- 
water fishes  are  absent.  The  family  of  Cyprinids,  those 
essentially  fresh- water  fishes  to  which  the  carp  belongs,  is 
well  represented  there.  Hence  if  we  suppose  that  they  were 
destroyed  during  the  invasion  of  that  region  by  the  sea,  the 
lakes  must,  at  a  subsequent  period,  have  been  freely  connected 
with  rivers  which  were  stocked  with  fresh -water  fish.  And 
it  appears  that  this  actually  has  been  the  case. 

Whether  the  St.  Lawrence  was  choked  by  obstructing  ice 
masses,  or  whether  it  was  filled  with  detrital  matter  carried 
down  from  the  neighbouring  eastern  heights,  does  not  affect 
our  present  inquiries.  It  seems  that  after  the  ice,  or,  if  we 
prefer  it,  after  the  retreating  sea,  had  left  the  district,  there 
were  only  three  lakes  instead  of  the  five  as  at  present.  These 
three  lakes,  which  have  been  called  "  Duluth,"  "  Chicago  " 
and  "Maumee,"  were  independent  of  one  another.  Lake 
Duluth  emptied  its  waters  into  the  Mississippi,  Lake  Chicago 
excavated  an  outlet  which  has  since  become  the  Chicago 
drainage  canal,  while  Lake  Maumee  communicated  with  the 
Wabash  River.  All,  of  course,  eventually  helped  to  swell  the 
waters  of  the  Mississippi.  Lake  Maumee  gradually  developed 
into  the  huge  Lake  Warren.  Later  on  the  other  lakes  joined, 
and  poured  their  waters  into  Ontario,  which  then  communi- 
cated with  the  Hudson  by  means  of  the  Mohawk  River.  It 
was  only  then  that  the  sea  finally  broke  down  the  barrier 
which  had  prevented  an  overflow  into  the  St.  Lawrence,  and 
advanced  as  far  as  the  western  end  of  Lake  Ontario,  one 
marine  channel  communicating  with  the  Atlantic  by  way 
of  the  Hudson  Valley. 

We  can  easily  imagine  how  the  fresh-water  fishes  of  the 
north,  which  were  either  killed  or  driven  south,  such  as  the 
redfin  (Notropis  cornutus)  and  Notropis  atherinoides  (it  does 
not  seem  to  possess  a  common  name)  managed  to  return  to 
their  northern  stations  after  the  Glacial  Epoch.  Yet  I  feel 
sure  that  a  survival  even  of  some  fresh-water  fishes  took  place 
within  the  drift  area  in  some  of  the  eastern  mountain  ranges. 
Near  Freeport  in  Maine,  quite  an  isolated  colony  of  the 
beautiful  red-bellied  dace  (Chrosomus  erythrogaster)  occurs. 
This  is  probably  a  pre-Glacial  relict.  Nor  is  it  likely  that 


FISHES   OF   GEEAT   LAKES  51 

the  silver  chub  (Semotilus  corporalis),  which  only  frequents 
clear  streams,  could  have  spread  in  post-Glacial  times  from 
the  south-eastern  counties  to  the  St.  Lawrence  basin.  Two 
more  examples  might  be  mentioned  that  are  practically, 
confined  to  the  drift  area  and  they  are  among  the  most 
interesting  geographical  puzzles  of  North  America. 

The  first  of  these  is  the  mud  minnow  (Umbra  limi),  a 
small  minnow-like  fish  frequenting  muddy  and  reedy  ponds 
near  the  Great  Lakes  as  far  east  as  Quebec.  A  closely  allied 
species  lives  in  streams  and  ponds  in  the  eastern  States  from 
Connecticut  to  South  Carolina.  The  only  other  relative  of 
these  two  little  fish,  in  fact  the  only  other  member  of  the, 
family  of  mud-minnows  (Umbridae),  is  Umbra  krameri  found 
in  Hungary.  Dr.  Gill*  gives  a  most  interesting  account: 
of  their  habits. 

Blanding's  pond  tortoise  (Emys  blandingi)  is  the  second 
example  I  have  in  my  mind.  It  is  a  small  species,  the  black 
carapace  or  shell  being  dotted  all  over  with  numerous  yellow 
spots.  It  is  entirely  confined  to  the  drift  region  from 
Wisconsin  in  the  west  to  New  Hampshire  in  the  east.  It 
agrees  with  Umbra  in  so  far  as  its  only  relation  inhabits 
Europe.  The  European  species  (Emys  orbicularis)  is 
common  in  central  and  southern  Europe.  A  map  of  its  range 
is  given  in  my  work  on  the  European  animals. f 

A  more  striking  instance  of  a  case  of  survival  within  the 
glaciated,  or  drift  area,  is  afforded  by  the  fresh-water  pearl- 
mussel  (Margaritana  margaritifera).  Being  an  immensely 
ancient  species  which  no  doubt  originated  in  North  America, 
it  has  taken  advantage  of  old  land  connections  to  invada 
Europe  and  east,ern  Asia.  In  North  America  it  occurs  within 
the  ancient  eastern  land-mass  in  several  localities,  notably 
in  Labrador,  on  Newfoundland  and  Anticosti  Islands,  in 
the  Quebec  province  and  in  New  England.  J  From  its  western 
station  in  the  lower  Saskatchewan  it  is  separated  by  a 
tract  of  over  one  thousand  two  hundred  miles  in  which 
it  is  unknown.  This  discontinuous  distribution  implies 

*  Gill,  Theodore,  "  The  Umbras." 

t  Scharff,  E.  P.,  "  European  Animals,"  p.  179. 

|  Walker,  Bryant,  "  Distribution  of  Margaritana  margaritifera,"  p.  127. 

E2 


52  ORIGIN   OF   LIFE   IN    AMERICA 

the  destruction  of  the  species  in  the  drainage  area  of  the 
Upper  St.  Lawrence.  What  other  cause  but  the  Glacial 
Epoch  can  be  assigned  for  this  partial  destruction  ?  And 
in  explanation  of  this  and  other  similar  cases  it  seems 
reasonable  to  conclude  that  certain  areas  within  the  drift 
region  were  entirely  free  from  the  devastating  agency,  be  it 
land -ice  or  the  sea,  which  destroyed  so  much  of  the  pre- 
existing fauna  and  flora.  We  might  argue,  of  course,  that  the 
pearl-mussel  had  advanced  northward  in  two  independent 
streams  in  post-Glacial  times,  one  along  the  Mississippi  valley 
and  the  other  along  the  Atlantic  coast,  and  that  they  had  thus 
reached  the  northern  habitats  alluded  to.  But  quite  apart 
from  the  difficulties  connected  with  pushing  its  way  along 
the  coast  from  river  to  river,  there  seem  to  me  to  be  no 
grounds  for  such  a  supposition.  The  fact  that  Margariiana 
margaritifera  is  the  only  fresh-water  mussel  (Naiad)  belong- 
ing to  the  Atlantic  river  system  which  is  now  found  living 
within  the  Mississippi  drainage  area,  shows  how  inconceiv- 
ably slowly  these  mollusks  spread.  The  fresh-water  mussel 
fauna,  so  characteristic  of  the  Mississippi  drainage  area,  is 
believed  to  have  descended  in  a  scarcely  broken  line  from  that 
of  the  Cretaceous  Period,  and  many  recent  forms  are  only 
distinguishable  with  difficulty  from  those  that  lived  in  those 
remote  times. 

However,  the  question  of  survival  or  non-survival  in  the 
drift  area  is  not  confined  to  the  instance  alluded  to.  Lampsilis 
(Unio)  borealis,  Lampsilis  superiorensis,  Anodonta  mar- 
ginata,  Anodonta  kennicotti,  and  Anodonta  pepiniana  are  all 
restricted  in  their  range  to  the  drift  area,  and  are  not  known 
to  have  ever  lived  outside  it.* 

There  is  no  doubt  ample  zoological  evidence  for  the  assump- 
tion that  many  species  of  vertebrates  and  invertebrates 
survived  the  Glacial  Epoch  within  the  area  commonly  sup- 
posed to  have  been  covered  by  vast  ice-masses.  But  there 
is  another  important  point  which  the  geographical  distribu- 
tion of  the  fresh- water  pearly  mussels  may  elucidate.  Several 
times  I  have  referred  to  the  theory  that  in  pre- Glacial  times 
the  land  between  northern  Labrador  and  eastern  Massa- 

*  Simpson,  C.  T.,  "  Synopsis  of  pearly  freshwater  mussels." 


FRESH-WATER   PEARL   MUSSELS  53 

chusetts  was  raised  to  a  much  higher  level  than  ifc  is  now, 
and  that  it  has  gradually  sunk  to  its  present  position.  If  this 
had  been  the  case,  the  rivers  on  the  western  side  of  this, 
highland  would  have  drained  westward  and  would  have 
formed  part  of  the  Mississippi  drainage,  while  the  eastern 
streams  would  have  emptied  their  waters  straight  into  the 
Atlantic.  The  latter  ought  therefore  to  show  distinct  signs 
in  the  composition  of  their  fauna  of  having  been  isolated 
from  the  Mississippi  drainage  system.  Dr.  Simpson  de- 
scribes the  fresh-water  pearl-mussels  of  the  Mississippi 
drainage  system  as  large,  ponderous  and  ornamented  with 
beautiful  and  odd  patterns  of  colour  and  sculpture.  The 
waters  that  drain  into  the  Atlantic  on  the  other  hand  are 
inhabited  by  a  totally  different  set  of  mussels.  They  are 
moderate  in  size,  frail  and  not  remarkble  for  either  colour 
or  sculpture.  Only  very  few  of  the  eastern  species  extend 
westward  to  the  head  waters  of  the  St.  Lawrence.* 

In  the  interesting  report  on  the  Pleistocene  fauna  and  flora 
already  cited,  there  is  a  list  of  twelve  species  of  fresh -water 
mussels  that  have  been  observed  in  the  Don  valley  deposits. 
None  of  them  belong  to  extinct  species,  though  it  is  a  signifi- 
cant fact  that  nearly  one  half  of  them  no  longer  inhabit  the 
St.  Lawrence  drainage,  being  now  confined  to  the  Mississippi 
and  its  tributaries.f 

This  certainly  implies  that  the  Mississippi  was  more  inti- 
mately connected  with  the  upper  St.  Lawrence  system  in 
early  Glacial  and  probably  in  pre-Glacial  times  than,  it  is  now, 
for  it  is  not  unjustifiable  to  assume  that  these  southern  forms 
found  their  way  northward  before  the  commencement  of  the 
Glacial  Epoch.  It  is  possible  that  those  southern  species, 
found  in  the  Don  deposits,  which  still  have  a  wide  range  in 
Canada,  may  have  survived  the  Glacial  Epoch  in  that  country. 
Dr.  Simpson  J  pointed  out  that  almost  all  the  Mississippi 
valley  species  of  mussels  now  living  in  St.  Lawrence  drain- 
age area  Jiave  become  more  stunted  and  more  simple  in 
outline,  while  their  characteristic  sculpture  and  colours  are 

*   Simpson,  0.  T.,  "  On  some  Fossil  TJnios."  pp.  591—592. 
t   Dawson,  J.  W.,  D.  P.  Penhallow,  &c.,  "  Canadian  Pleistocene  Flora 
and  Fauna,"  p.  331. 

J  Simpson,  C.  T.,  "On  Mississippi  Valley  Unionidae,"  p.  384. 


54  OKIGIN    OF   LIFE   IN   AMERICA 

nearly  obliterated.  This  change  in  form  is  so  striking, 
says  Dr.  Simpson,  that  many  of  these  northern  races  of 
Mississippi  mussels  have  been  described  as  distinct  species. 
Dr.  Simpson  is  of  opinion  that  this  remarkable  change  in 
form  among  the  Mississippi  species  inhabiting  the  St.  Law- 
rence drainage  system  has  been  produced  since  the  Ice  Age 
began  to  draw  to  a  close,  because,  he  argues,  it  is  almost 
certain  that  all  fluviatile  and  lacustrine  life  under  the  ice 
sheet  was  destroyed. 

The  prevalent  geological  opinions  as  to  the  nature  of  the 
Ice  Age  thus  dominate  all  biological  thought  in  reference  to 
problems  of  distribution.  If  we  emancipate  ourselves  from 
these  pre-conceived  notions  in  our  speculations  on  the  origin 
of  the  existing  fresh-water  mussel  fauna,  we  must  arrive  at 
different  conclusions. 

Two  almost  diametrically  opposed  theories  have  been  pro- 
pounded to  explain  the  origin  of  the  geographical  features 
of  the  river  system  of  north-eastern  North  America  in  pre- 
Glacial  times.  According  to  Professor  Grabau,*  Mr.  Warren 
Upham  and  Professor  I.  C.  Russell  are  of  opinion  that  the 
greater  part  of  the  Laurentian  basin  formerly  discharged  its 
waters  southward  to  the  Mississippi.  With  this  view  Professor 
Grabau  agrees.  Much  of  the  Archaean  region  in  north-eastern 
North  America  must  have  stood  greatly  higher  than  at  present, 
the  slope  of  the  land  being  toward  the  south-west.  Two  great 
rivers  then  existed,  according  to  Professor  Grabau,  in  place 
of  the  present  Great  Lakes,  the  Saginaw  and  the  Dundas 
Rivers,  both  of  them  draining  into  the  ancient  Mississippi. 
Dr.  Spencer  is  in  agreement  with  Dr.  Grabau  in  so  far  as  he 
contends  that  the  land  stood  at  least  two  thousand  feet  higher 
than  at  present.  He  differs  from  the  other  writers  in  his 
belief  that  the  lake  region  and  the  more  north-easterly  high- 
lands were  equally  affected  by  the  uplift,  so  that  the  rivers 
which  replaced  the  lakes  in  pre-Glacial  times  drained  into 
the  St.  Lawrence  just  as  the  waters  from  the  lakes  do  now.f 

The  first  of  these  two  theories  seems  to  me  to  explain  the 
origin  of  the  eastern  fauna  in  a  satisfactory  manner.     The 

*  Grabau,  A.  W.,  "  Geology  of  Niagara  Falls,"  pp.  42—54. 
T  Spencer,  J.  W.,  "Falls  of  Niagara,"  pp.  400—405. 


HISTORY   OF   THE   GREAT  LAKES  55 

other  does  not.  We  may  suppose  that  the  species  inhabit- 
ing the  Mississippi  during  the  period  preceding  the  Ice  Age 
were  not  precluded  from  advancing  up  stream  towards  the 
highlands  of  Labrador.  But  only  the  hardiest  forms,  those 
that  could  adapt  themselves  to  waters  probably  brackish  and 
laden  with  mud,  might  have  succeeded  in  surviving,  though 
not  without  becoming  stunted  in  form  and  undergoing 
various  other  changes.  Such  forms  as  the  pearl-mussel 
(Margaritana  margaritifera),  accustomed  to  pure  mountain 
streams,  only  survived  in  isolated  localities  in  the  eastern  and 
western  parts  of  its  range,  becoming  extinct  in  the  central 
parts,  where  the  conditions  must  have  been  less  favourable  for 
its  survival. 

Let  us  now  examine  the  land  fauna  of  another  part  of 
this  north-eastern  Archaean  land  surface  which  is  supposed 
by  Professors  Upham  and  Grabau  to  have  stood  at  a  rela- 
tively much  higher  level  to  the  lake  region  than  it  does  at 
present.  Labrador  has  been  amply  dealt  with,  but  New- 
foundland, which  must  have  been  completely  isolated  from 
the  mainland  for  some  time  past,  being  a  large  island  situated 
at  the  mouth  of  the  mighty  St.  Lawrence  River,  ought 
to  contain  some  interesting  pre-Glacial  relicts.  We  have  no 
reason  to  assume  that  Newfoundland  has  been  connected 
with  the  mainland  since  the  passing  away  of  the  Ice  Age, 
nor  is  there  any  evidence  to  show  that  mammals  or  other 
terrestrial  vertebrates  have  reached  the  island  by  swimming 
across  the  Strait  of  Belleisle  or  down  the  St.  Lawrence.. 
Geologists  tell  us  that  Newfoundland  was  not  overridden 
by  the  huge  Labrador ean  glacier,  but  that  it  had  a  system 
of  local  glaciers  quite  independent  of  those  of  the  mainland. 
Even  if  all  the  higher  parts  of  the  island  had  been  buried 
in  snow  and  ice,  tracts  of  land  near  the  coast  must  have 
remained  free  from  ice,  as  in  Greenland,  and  so  have  given 
shelter  to  the  survivors  from  pre-Glacial  times.  This  view 
is  certainly  strengthened  by  the  fact  that  all  the  mammals 
hitherto  observed  on  the  island  belong  to  well-marked  varieties 
or  species  peculiar  to  it.  The  Newfoundland  caribou,  the 
only  deer  inhabiting  the  island,  has  antlers  differing  con- 
spicuously from  those  of  other  races  of  reindeer,  and  many 
authorities  now  recognise  it  as  a  distinct  species  under  the 


56  OEIGIN   OF   LIFE    IN   AMERICA 

name  of  Eangifer  terraenovae.  All  reindeer  are  expert 
swimmers,  yet  the  Newfoundland  reindeer  or  caribou  has 
never  been  known  to  cross  over  to  the  mainland.  The  follow- 
ing other  gpecies  of  mammals  are  all  peculiar  to  Newfound- 
land. The  Newfoundland  musk  rat  (Fiber  obscurus),  the 
Newfoundland  vole  (Microtus  terraenovae),  the  Newfound- 
land arctic  hare  (Lepus  bangsi),  the  Newfoundland  lynx 
(Lynx  subsolanus),  the  Newfoundland  fox  (Vulpes  deletrix), 
the  Newfoundland  otter  (Lutra  degener),  the  Newfoundland 
marten  (Mustela  atrata).  A  bear  and  a  wolf  are  also  said  to 
occur. 

The  fauna  of  Newfoundland,  moreover,  is  characterised  by 
the  remarkable  absence  of  all  such  mammals  which  we  might 
reasonably  expect  to  have  come  from  Asia  in  comparatively 
recent  geological  times,  such  as  the  moose,  wapiti  deer,  brown 
bear  and  many  smaller  species.  The  island  does  not  seem 
to  have  been  affected  by  the  great  stream  of  new-comers  which 
poured  into  the  country  and  reached  other  parts  of  eastern 
America,  such  as  Nova  Scotia. 

In  speaking  of  the  present  land  bird  fauna  of  Nova  Scotia, 
Dr.  Trotter  argues  that  it  was  derived  from  two  faunal 
stocks,  a  more  primitive  boreal  one  which  occupied  the  region 
from  remote  times,  and  a  later  transition  fauna  which  in- 
vaded the  peninsula  since  the  re- elevation  of  the  previously 
sunken  isthmus.  He  speaks  of  this  as  a  "  venturesome  state- 
ment," yet  he  suggests  that  many  boreal  types  belonging 
to  the  genera  Pinicola,  Carpodacus,  Loxia,  Spinus,  Sitta, 
Eegulus,  Certhia  and  Parus  may  have  occupied  Nova  Scotia 
even  during  the  Glacial  Epoch,  since  glaciers  do  not  preclude 
forest  growth,  while  food  must  have  been  abundant  during 
the  short  breeding  season.* 

It  has  been  my  intention  in  this  chapter  to  briefly  direct 
attention  to  the  extreme  north-east  as  one  of  the  salient 
bio -geographical  features  of  the  American  continent.  More 
than  fifty  years  ago  Professor  L.  Agassiz  spoke  of  "  the 
zoological  island  of  New  England,"  which  he  described  as 
encircled  by  a  uniform  combination  of  fresh -water  animals, 

*  Trotter,  Spencer,  "  Land  Bird  Fauna  of  North -Eastern  America," 
p.  226. 


ANIMALS   OF    NEWFOUNDLAND  57 

being  itself  isolated  in  character  and  approaching  more  to 
that  of  the  Old  World.*  He  was  then  unaware  that  this  zoo- 
logical island,  which  his  keen  insight  and  judgment  had 
recognised,  extended  really  far  to  the  north  of  New  England, 
that  it  formed  part,  in  fact,  of  the  north-western  prolongation 
of  the  European  continent  in  late  Pliocene  times,  preserving 
until  the  present  day  many  characters  in  common  with  the 
Old  World. 

*  Agassiz,  L.,  "  Fishes  of  the  Tennessee,"  pp.  363—364. 


CHAPTER  III 

THE    CANADIAN    NORTH    WEST 

LEAVING  Newfoundland,  the  St.  Lawrence  and  the  region 
of  the  Great  Lakes  on  our  north-westward  travels,  we  now 
enter  the  drainage  area  of  the  mighty  Mackenzie  River  which 
conducts  its  muddy  waters  to  the  Arctic  Ocean.  We 
know  from  Mr.  A.  H.  Harrison's  *  recent  exploit  that  it 
is  possible  to  journey  down  the  one  thousand  eight  hun- 
dred miles  from  the  Athabaska  landing  and  reach  the  Arctic 
Ocean  entirely  by  boat.  But  we  obtain  a  better  idea  of  the 
fauna  and  flora  of  this  vast  Athabaska-Mackenzie  region  by 
crossing  the  country  on  foot,  or  by  a  perusal  of  the  excellent 
report  lately  published  by  the  biological  survey  of  the  United 
States  Department  of  Agriculture.  The  task  of  furnishing 
this  report  was  entrusted  to  Mr.  Edward  A.  Preble,f  a  natura- 
list who  already  had  the  advantage  of  accomplishing  the  diffi- 
cult survey  of  the  Hudson  Bay  region,  and  who  had  shown 
himself  possessed  of  the  necessary  qualifications  for  such  an 
undertaking. 

The  Mackenzie  basin  comprises  a  vast  region  of  nearly 
700,000  square  miles,  or  about  six  times  the  size  of  the 
British  Islands.  As  is  usually  the  case  in  regions  covered 
by  glacial  drift,  the  country  is  studded  with  innumerable 
fresh-water  lakes  extending  in  a  more  or  less  connected  system 
from  Lake  Superior  to  the  Arctic  Ocean.  With  the  exception 
of  a  large  area  in  the  north,  which  is  mainly  outside  the  actual 
drainage  basin  of  the  Mackenzie,  much  of  this  region  is 
entirely  covered  with  forests.  The  principal  trees  are  white 
and  black  spruce,  the  canoe  birch,  tamarack,  aspen  and  balsam 

*  Harrison,  A.  H.,  "In  Search  of  a  Polar  Continent." 
t  Preble,  E.  A.,    "  Athabaska-Mackenzie   Kegion."      Compare   also 
Macfarlane,  K.,  "  Mammals  of  North- West  Territory." 


THE   MACKENZIE   BASIN  59 

poplars,  Banksian  pine  and  balsam  fir.  With  these  are  asso- 
ciated, generally  in  the  form  of  undergrowth,  a  variety  of 
shrubs,  some  of  which  have  a  continuous  distribution  through 
the  forest  zone,  whereas  others  are  more  or  less  restricted 
in  range.  But  the  whole  region  between  Hudson  Bay  and 
the  mouth  of  the  Mackenzie  River  is  by  no  means  all  forested. 
North  of  a  line  drawn  from  the  mouth  of  the  Churchill  River 
to  the  mouth  of  the  Mackenzie,  the  country  belongs  to  what 
are  known  as  the  "  barren-grounds,"  which  have  already  been 
alluded  to  in  previous  chapters.  They  are  largely  covered 
with  short  grass,  moss  and  small  flowering  plants  interspersed 
with  patches  of  sedgy  or  peaty  soil  on  which  grow  Labrador 
tea,  crowberries,  dwarf  birches,  and  willows.  Both  flora 
and  fauna,  in  fact,  remind  us  vividly  of  certain  parts  of  Green- 
land and  Labrador. 

The  only  large  mammals,  as  in  Greenland,  are  the  barren- 
ground  caribou  and  the  musk  ox.  The  former  is  simply 
spoken  of  as  the  "  deer  "  by  the  northern  hunters.  Zoologi- 
cally it  belongs  to  the  barren-ground  form  (Rangifer  arcticus) 
which,  as  I  remarked,  seems  to  be  closely  allied  to  the  Green- 
land reindeer.  It  is  not  so  with  the  musk  ox,  as  Dr.  Kowarzik 
has  recently  shown.  After  a  very  careful  and  extended  ex- 
amination of  a  number  of  skins  and  skulls  of  musk  oxen 
from  this  region,  he  was  able  to  show  that  they  differed  from 
those  living  elsewhere  by  the  possession  of  a  deep  lachrymal 
pit  and  two  mammary  glands.  The  Greenland  musk  o<x,  which 
belongs  to  the  eastern  group,  has  no  lachrymal  pit  and  four 
mammary  glands.  There  are  other  minor  differences  clearly 
proving  that  Dr.  Kowarzik's  *  Ovibos  moschatus  macken- 
zianus  is  much  more  than  a  mere  race.  It  is,  in  fact,  a  species 
perfectly  distinct  from  the  on©  inhabiting  Greenland.  In 
spite  of  these  differences,  the  casual  observer  is  easily  misled 
by  the  apparent  external  resemblances  among  all  the  musk 
oxen. 

The  general  similarity  in  the  fauna  of  the  Mackenzie 
region  and  that  of  Greenland  is  by  no  means  super- 
ficial, and  holds  good  to  some  extent  even  among  the  smaller 
kinds  of  beasts.  The  arctic  hare  seems  much  like  the  Green- 

*  Kowarzik,  E.,  "  Der  Moschusochs  und  seine  Kassen,"  p.  120< 


60  ORIGIN   OF   LIFE   IN   AMERICA 

land  hare,  and  the  lemmings  resemble  the  creatures  we  have 
already  met  in  the  same  country.  Yet  there  are  two  perfectly 
distinct  kinds  of  lemming  in  these  barren-grounds.  In  winter 
they  are  easily  discriminated  since  one  of  them  does  not 
change  its  rusty  brown  fur,  while  the  other  (Dicrosfconyx 
hudsonius)  becomes  white  all  over.  The  former  we  have  not- 
met  with  before.  It  neither  occurs  in  Greenland  nor  in 
Labrador,  and  appears  to  be  a  more  recent  immigrant 
to  North  America.  This  supposition  is  strengthened  by 
the  fact  of  the  occurrence  of  this  lemming  (Lemmus 
trimucronatus)  from  Alaska  as  far  east  as  Melville  Penin- 
sula. In  Alaska  even  another  species  of  the  same  genus 
(Lemmus  minusculus)  occurs,  and  on  the  Pribilof  Islands 
still  another,  the  black-footed  lemming  (Lemmus  nigripes) 
Beyond  Bering  Strait  in  eastern  Asia  other  kinds  make  their 
appearance,  whilst  in  Europe  the  common  lemming  (Lemmus 
lemmus)  was  well  known  long  before  the  days  of  Linnaeus. 
Its  remains  having  been  discovered  in  many  European  caves 
along  with  those  of  other  arctic  animals,  it  is  not  unreason- 
able to  assume  that  the  genus  Lemmus  is  of  Old  World  origin 
and  one  of  the  many  Asiatic  immigrants  that  have  invaded  the 
North  American  continent  in  the  past,  though  only  a  few  of 
the  latter  have  chosen  the  inhospitable  barren  grounds  for 
their  home. 

Another  new  form  which  we  have  not  met  with  before 
is  the  ground  squirrel  known  as  the  Hudson  Bay  spermophile 
(Citellus  partryi).  It  is  abundant  all  over  the  barren-ground 
region  alluded  to,  the  earth  being  occasionally  riddled  with 
their  burrows.  These  "  spermophiles  "  or  "  gophers  "  as  they 
are  sometimes  called,  occupy  a  somewhat  intermediate  posi 
tion  between  squirrels  and  marmots.  Numerous  species  are 
known  from  North  America,  altogether  about  forty.  In  Asia 
and  Europe  there  are  fewer  kinds  of  spermophiles,  yet  they 
do  occur,  and  this  circumstance,  while  tending  to  prove  once 
more  that  Bering  Strait  was  dry  land,  renders  the  search 
for  the  original  home  of  the  genus  more  difficult.  The  fact 
that  in  Europe  Citellus (Spermophilus)  only  inhabits  the  east, 
having  invaded  the  continent  in  Pleistocene  times,  and  then 
retreated  again  towards  the  country  whence  it  came,  points 
to  Asia  as  the  home  of  the  spermophiles.  On  the  other  hand, 


LEMMINGS   AND   GOPHEES  61 

the  remains  of  Citellus  douglasi  have  been  recorded  from 
P,otter  Creek  cave  in  California,  and  those  of  Citellus  tride- 
cemlineatus  from  the  Conard  fissure  in  Arkansas.  Both  of 
these  deposits  are  regarded  as  Pleistocene  in  age.*  If  these 
caves  were  in  Europe  they  certainly  would  be  held  'to  be  pre- 
Glacial,  for  about  fifty  per  cent,  of  the  species  contained  in 
them  are  extinct,  while  Mastodon,  Megalonyx  and  other 
ancient  forms  accompany  the  spermophiles  in  the  Cali- 
fornian  cave.  The  two  spermophiles  alluded  to  are  still 
living  in  North  America  and  have  a  wide  range.  If  the  genus 
had  invaded  Alaska  from  Asia  in  Pleistocene  times,  it  is 
gcarcely  credible  that  there  would  have  been  time  for  the 
development  of  the  two  species  and  their  enclosure  in  these 
distant  caves  within  the  Pleistocene  Period,  especially  when 
we  consider  that  the  whole  of  Canada  is  believed  to  have  been 
buried  under  a  thick  mantle  of  ice.  It  is  possible,  of  course, 
that  there  were  two  distinct  invasions  into  North  America  of 
the  genus  Citellus,  one  having  entered  from  the  west,  as  I 
shall  explain  later  on,  in  Miocene  times,  the  later  one  from 
the  north-west  towards  the  end  of  the  Pliocene  Period. 

Among  the  carnivores  of  the  barren  grounds,  the  barren- 
ground  bear  (Ursus  richardsoni),  the  wolverine  (Gulo  luscus), 
and  the  barren-ground  wolf  (Canis  occidentalis  albus)  are 
the  most  noticeable. 

I  have  scarcely  as  yet  attempted  to  bring  the  study  of 
the  geographical  distribution  of  birds  within  the  scheme  of 
this  present  work,  partly  because  our  knowledge  of  their  past 
history  is  so  defective  in  comparison  with  that  of  many  other 
groups,  and  partly  because  mountain  ranges  or  narrow 
channels  of  the  sea  do  not  as  a  rule  afford  effective  barriers 
to  their  dispersal.  Occasionally,  however,  birds  are  extremely 
circumscribed  in  their  range,  and  there  can  be  no  doubt  that  a 
study  of  their  geographical  distribution  is  well  worthy  of  care- 
ful attention.  If  I  had  not  a  superabundance  of  better  material 
for  my  purpose,  I  should  gladly  dwell  a  little  longer  on  the 
problems  suggested  by  their  range.  Many  of  them,  however, 
are  quite  useless  for  our  purpose,  loons  and  auks,  for  instance, 
two  groups  of  arctic  birds  attached  to  the  sea  coast.  Many 

*  Brown,  Barnum,  "  Conard  Fissure,"  pp.  166 — 167. 


62  OKIGIN   OF   LIFE   IN   AMEEICA 

others  are  circumpolar  but  too  migratory.  Only  the  genus 
Lagopus  is  of  special  interest,  because  it  occurs  in  all  the 
regions  and  countries  so  far  discussed.  It  includes  the 
American  and  Old  World  ptarmigans  and  the  European 
grouse,  all  of  which  are  more  or  less  permanently  resident  in 
the  countries  they  inhabit. 

The  willow  ptarmigan  (Lagopus  albus)  breeds  in  the 
barren-grounds  and  further  south.  It  has  a  very  wide  range, 
inhabiting  northern  Asia,  northern  Eussia,  and  northern 
and  central  Scandinavia.  It  is  not  found  in  Greenland  or 
Newfoundland,  being  replaced  there  by  the  rock  ptarmigan 
(Lagopus  rupestris).  The  latter  also  lives  in  Iceland, 
western  Asia,  arctic  America  and  Japan.  The  third  American 
species  is  the  white-tailed  ptarmigan  (Lagopus  leucurus) 
which  frequents  the  Eocky  Mountain  summits  from  Alaska 
to  New  Mexico.  It  is  sometimes  called  the  "  white  or  snow- 
quail."  Besides  the  willow  ptarmigan,  we  have  in  Europe  the 
common  ptarmigan  (Lagopus  mutus),  the  red  grouse  (Lagopus 
scoticus),  peculiar  to  the  British  Islands,  and  Lagopus  hyper- 
boreus  of  Spitsbergen  arid  Franz  Josef  Land.  Long  ago  I 
ventured  to  express  the  opinion  that  the  genus  Lagopus  was 
of  North  American  origin  having  thence  spread  to  Europe 
and  Asia.* 

Dr.  Stejnegert  has  since  pointed  out  that,  by  an  unfortunate 
oversight,  I  had  included  Greenland  in  the  range  of  the  willow 
ptarmigan  instead  of  the  rock  ptarmigan.  He  also  argued 
that  the  willow  ptarmigan  of  Scandinavia  is  more  likely  to 
have  originated  from  the  British  red  grouse  than,  as  I  thought, 
vice  versa.  Though  I  still  believe  that  the  genus  had  a 
North  American  ancestry,  I  quite  concur  with  Dr.  Stejneger 
in  the  view  that  the  points  he  raised  cannot  be  reconciled 
with  the  conclusions  I  formerly  arrived  at.  The  subject  is 
certainly  worthy  of  further  careful  study.  At  any  rate,  this 
instance  shows  clearly  the  much  greater  difficulties  we  have 
to  contend  with  in  tracing  the  geological  history  of  birds 
than  that  of  mammals. 

As  we  proceed  southward  from  the  barren-grounds  we  first 

*  Scharff,  E.  F.,  "  History  of  European  Fauna,"  p.  336. 
t  Stejneger,  L.,  "  Scharff's  European  Fauna,"  p.  105. 


AMEEICAN   PTARMIGANS  63 

enter  a  belt  of  more  or  less  stunted  timber  before  reaching  the 
real  forest.  Yet  even  here  quite  a  number  of  new  forms  of 
animal  life  are  met  with  that  are  quite  absent  in  the  more 
northerly  districts.  They  are  mostly  species  occurring  also 
in  the  forest  zone  of  western  Labrador.  In  referring  to  them 
in  the  last  chapter,  I  alluded  more  fully  to  the  geological 
history  of  the  moose  (pp.  32 — 33),  but  I  dwelt  also  on  the  fact 
that  the  flying  squirrel,  musk  rat,  .chipmunk,  woodchuck  and 
others  made  their  appearance  as  soon  as  we  entered  the 
forest  from  the  east.  And  it  is  precisely  these  forms  of  animal 
life  that  make  such  a  change  in  the  Appearance  of  the  fauna 
as  we  leave  the  Mackenzie  region  barren-grounds  on  our 
way  to  the  great  Canadian  forest  region. 

The  flying  squirrel  (Sciuropterus  sabrinus)  of  northern 
Canada  and  arctic  America  is  also  found  further  south.  Other 
species  of  the  same  genus  inhabit  the  United  States.  The 
skin  at  the  sides  of  its  body  extends  between  the  limbs  in 
such]  a  manner  as  to  act  like  a  kind  of  parachute,  butf  nothing 
in  the  nature  of  actual  flight  takes  place.  The  flying 
squirrel  is  rarely  seen,  being  an  entirely  nocturnal  crea- 
ture. The  distribution  of  these  flying  squirrels  is  decidedly 
interesting.  They  are  found  from  Florida  to  Alaska,  and 
are  only  known  as  fossils  from  the  Potter  Creek  Cave  in 
California,  They  have  almost  certainly  been  in  the  country 
since  Pliocene  times.  Hence  Sciuropterus  yukonensis,  which 
is  peculiar  to  Alaska,  has,  in  all  probability,  survived  the 
Glacial  Epoch  in  that  country.  On  the  western  side  of  Bering 
Strait,  in  Kamchatka,  another  species  is  found  whose  range 
extends  westward  as  far  as  Scandinavia.  Southward,  as 
we  cross  China  into  Burma  and  India,  we  still  encounter 
species  of  flying  squirrels,  and  even  on  the  islands  of 
Java,  Sumatra  and  Borneo.  And  all  these  belong  to  the  same 
genus  Sciuropterus.  Such  an  extensive  distribution  implies 
that  the  genus  must  be  an  ancient  one,  and,  indeed,  we  are 
acquainted  with  several  species  of  Sciuropterus  from  the, 
Miocene  and  Pliocene  deposits  of  France.  This  in  itself  is 
no  proof  that  the  flying  squirrels  originated  in  Europe.  They 
may  have  spread  there  from  Asia  in  later  Tertiary  times  and 
have  subsequently  died  out  in  Europe,  only  to  be  re-estab- 
lished more  recently  from  a  later  Asiatic  invasion.  In  any 


64  OEIGIN   OF   LIFE   IN   AMERICA 

case,  the  presence  of  flying  squirrels  in  America  seems  to  be 
due  to  a  migration  from  Asia,  and  that  this  took  place  at  a 
time  when  a  land  bridge  existed  between  the  two  continents 
is  evident. 

Th,e  musk  rat  (Fiber  zibethicus)  *  derives  its  popular  fame 
chiefly  Irom  the  fact  that  thousands  of  its  skins  are  annually 
exported  from  North  America  by  the  fur  traders.     Having 
adopted  the  more  attractive  name  of  "musquash"  for  these 
skins,  the  dealers  have  no  difficulty  in  disposing  of  them.  Like 
beavers,  these  creatures  inhabit  subterranean  burrows  on  the 
banks  of  lakes  and  streams,  and  are  expert  swimmers,  yet  they 
are  really  more  allied  to  the  voles.    Varieties  of  the  common 
musk  rat  are  met  with  from  the  Mackenzie  River  to  Labrador 
and  southward  as  far  as  New  Mexico.    In  the  Yukon  district 
and  westward  Fiber  spathulatus  replaces  the  common  musk 
rat ;   and  far  to  the  east  in  Newfoundland  the  district  dusky 
musk  rat  (Fiber  obscurus)  occurs.      Only  two  other  living 
kinds   of  musk  rat  are  known  to  science.     One   of  them 
inhabits  the  State  of  Oregon,  the  other  the  dismal  swamp 
in  Virginia.      This   genus,   therefore,    is   one   of   the   most 
typically  North  American  we  have  noticed  so  far,  and  no 
doubt  it  has  originated  in  North  America.     This  view  is 
entirely    confirmed    by    fossil    evidence,    for   no   musk    rat 
remains  are  known  outside  North  America.     The  common 
musk   rat   has   been   observed   in  the   Pleistocene   deposits 
of  South   Carolina,   New  Jersey,    and   Pennsylvania,   while 
the  jaw  of  an  extinct  species   (Fiber  annectens)   has  been 
found  by  Mr.   Barnum  Brown  f  in  the  Conard  fissure  of 
Arkansas.     The  remarkable  circumstance  about  this  jaw  is 
that  the  teeth  it  contains  strongly  resemble  those  of  Neofiber, 
a  sub-genus  of  Microtus.      Hence  this  cave  species  forms  a 
connecting  link  between  the  genera  Fiber  and  Microtus,  and 
this  fact    supports   the   opinion  I  ventured  to  put  forward 
(p.  29)  as  to  the  American  origin  of  the  latter. 

Before  describing  some  of  the  other  small  beasts,  I  must 
refer  now  to  an  animal  which  is  not  only  the  largest  living 
terrestrial  American  mammal,  but  likewise  one  that  we,  from 

*  Hollister,  N.,  "  Synopsis  of  Muskrats." 

f  Brown,  Barnum,  "  Conard  Fissure,"  p.  197. 


FIG.  5. — Map  of  North  America,  showing  the  original  distribution  of  the  Bison  (lightly 
shaded),  the  range  of  the  same  animal  after  the  completion  of  the  Union  Pacific 
Railroad  (darkly  shaded),  and  the  present  range  in  Yellowstone  Park  (black). 
(Reproduced  with  Dr.  Hornaday's  permission.) 


[To  face  p.  65. 


HISTORY  OF  THE  BISON  65 

a  European  point  of  view,  are  accustomed  to  associate  above 
all  with  North  America,  namely,  the  bison,  or  so-called  buffalo. 

The  bison  (Bison  bison)  is  now  almost  extinct  in  its  wild 
state,  yet  here  in  the  Mackenzie  region,  ,a  little  to  the  south  of! 
the  Great  Slave  Lake,  are  still  found  some  wild  herds  of  this 
magnificent  creature,  the  last  remnants  of  the  millions  that 
once  roamed  over  the  continent. 

Dr.  Howard*  contributed  many  years  ago  an  interesting 
article  to  "  Science  "  on  the  manner  in  which  insects  and 
other  creatures  are  disseminated  over  the  States  through  the 
agency  of  man.  An  equally  instructive  paper  might  be  written 
on  the  manner  in  which  man  has  been  the  means  of  destroy- 
ing a  portion  of  our  fauna.  For  no  one  can  doubt  that  human 
agency  alone  is  responsible  for  the  rapid  destruction  of  the 
bison  and  other  animals. 

When  the  Spaniards  landed  in  America  in  the  year  1521, 
the  bison  was  still  plentiful  in  Northern  Mexico.  In  the  com- 
mencement of  the  following  century  the  English  found  it  in 
abundance  in  the  neighbourhood  of  the  present  site  of  the  city 
of  Washington.  No  doubt  the  range  of  this  huge  ungulate 
extended  over  about  one-third  of  the  entire  continent  of  North 
America.  The  extreme  south-eastern  limit  was  on  "the  coast  of 
Georgia.  The  western  boundary  was  in  New  Mexico.  From 
these  two  southern  localities  to  the  shores  of  the  Great  Slave 
Lake  in  Canada,  vast  herds  of  bison  were  known  to  exist  even 
in.  the  early  parts  of  the  last  century.  According  to  Dr. 
Hornaday's  f  graphic  description,  they  lived  and  moved,  as  no 
other  quadrupeds  ever  had,  in  great  multitudes,  like  grand 
armies  in  review,  covering  scores  of  square  miles  at  once. 
They  were  so  numerous  that  boats  were  sometimes  stopped 
by  them  in  the  rivers,  and  they  threatened  to  overwhelm 
travellers  on  the  plains.  In  later  years  they  occasionally 
derailed  locomotives  and  cars.  One  herd,  seen  by  Colonel 
Dodge  in  1871,  only  forty  years  ago,  and  described  by  him, 
extended  for  a  distance  of  twenty-five  miles  and  must  have; 
included  a  million  individuals.  The  Indians  believed  that 
these  buffaloes  issued  from  the  earth  continuously,  the 

*  Howard,  L.  O.,  "  The  Spread  of  Species  by  the  Agency  of  Man." 
t  Hornaday,  W.  T.,  "  Extermination  of  American  Bison." 

L.A-  F 


66  OBIGIN  OP  LIFE  IN  AMERICA 

supply  being  consequently  inexhaustible.  As  long  as  these 
wild  tribes  only  possessed  the  bow  and  arrow,  bisons  were 
comparatively  safe  from  their  depredations,  in  spite  oJ  the 
great  drives  that  they  were  accustomed  to  organise.  On  the 
introduction  of  firearms,  the  Indians  assisted  civilised  man 
to  the  best  of  their  ability  in  his  utterly  wanton  destruction 
of  these  helpless  creatures.  The  building  of  railroads  across 
the  continent  naturally  hastened  the  process  of  extermination, 
the  completion  of  the  Union  Pacific  line  dividing  for  ever 
the  bisons  of  the  United  States  into  two  great  herds.  These 
subsequently  became  known  as  the  northern  and  southern 
herds.  The  great  slaughter  of  the  bison  really  only  began 
in  1871.  Four  years  later  the  southern  herd  had  ceased  to 
exist.  The  year  1881  witnessed  a  similar  destruction  of  the 
northern  herd,  and  at  present  this  most  picturesque  and  im- 
pressive member  of  the  American  fauna  is  practically  extinct 
in  its  wild  state,  but  for  the  small  herds  alluded  to  in  northerii 
Canada  (see  Fig.  5).  There  are  other  small  herds  preserved 
in  the  Yellowstone  Park  and  in  some  reservations  in  western 
Canada.  In  them  the  bison  can  no  longer  be  said  to  live 
altogether  in  the  wild  state. 

I  mentioned  that  the  bison  was  looked  upon  as  one  of  the 
most  typically  American  species.  Nevertheless,  we  have  in 
eastern  Europe  a  bison  which  is  closely  allied  to  the  American 
species,  and  from  the  circumstance  that  it  formerly  roamed 
over  a  large  part  of  that  continent,  it  might  be  argued  that  its 
cousin  from  the  New  World  is  but  a  new-comer  and  in  no  way 
typical  of  America.  A  certain  amount  of  support  for  that 
argument  might  be  derived  from  the  well-known  fact  of  a 
Pliocene  bison  (Bison  sivalensis)  being  known  from  India 
and  Java  and  another  from  China.  But  in  America  there  are 
likewise  bison  remains  (Bison  alleni)  which  were  considered 
by  Professor  Marsh  to  belong  to  the  Pliocene  series,  while 
Professor  Cope  described  one  even  from  Nicaragua  and 
Southern  Mexico  (Bison  scaphoceras) .  More  recently,  how- 
ever, Dr.  Lucas  *  has  clearly  demonstrated  that  Cope's  bison 
is  a  sheep,  and  that  Marsh's  specimens  are  probably  referable 
to  the  lower  Pleistocene,  so  that  it  does  seem  likely  after 

*  Lucas,  F.  A.,  "Fossil  Bisons  of  North  America,"  pp.  756—766. 


WAPITI  DEER  67 

all  that  the  ancestors  of  the  American  bison  came  originally 
from  Asia.  The  exact  geological  period  of  this  supposed 
Asiatic  invasion  will  be  discussed  in  the  next  chapter,  when'  we 
come  to  deal  with  Alaska.  Some  other  extinct  bisons  are 
known  from  America  besides  those  alluded  to.  Bison  crassi- 
cornis,  according  to  Dr.  Lucas,  is  confined  to  Alaska.  Mr. 
Lydekker,  *  on  the  other  hand,  considers  it  identical  with 
Bison  priscus,  an  extinct  bison  which  ranged  throughout 
arctic  Siberia  and  a  large  part  of  Europe. 

South  of  the  belt  of  stunted  timber  lie  the  vast  forests 
of  the  Athabaska  and  Peace  Eiver  valleys,  and  a  great  zone 
of  warmer  country  abounding  in  animal  life,  as  we  proceed 
in  the  same  direction.  A  noble  representative  of  the  deer 
tribe  which  we  meet  here  reminds  us  of  the  European  red 
deer.  In  the  States  it  is  commonly  known  as  the  elk  (Cervus 
canadensis),  though  it  has  no  connection  with  the  moose, 
which  in  Europe  is  known  by  that  name.  In  Canada  it  is 
more  generally  called  "  wapiti  deer."  While  the  range  of 
the  moose  seems  to  be  on  the  increase  in  the  Mackenzie 
Region,  it  is  curious  that  the  wapiti  has  become  almost  extinct 
in  the  northern  parts  of  its  former  geographical  range,  and 
now  only  occurs  there  in  small  numbers. 

Mr.  Thompson  Seton  f  tells  us  that  originally,  that  is  to 
say  about  the  beginning  of  the  sixteenth  century,  the  wapiti 
was  found  from  the  Mackenzie  Region  as  far  east  as  Boston, 
and  as  far  south  as  Arizona  and  Alabama  (see  Fig.  6).  Its 
destruction  proceeded  unchecked  until  the  year  1895,  when  a 
change  in  public  opinion  took  place.  Henceforth  the  wapiti 
was  protected ;  and  it  is  now  actually  on  the  increas;e  in 
Manitoba  and  along  the  Rocky  Mountains  from  Alberta  to 
the  borders  of  New  Mexico  and  also  along  the  Pacific  States. 

The  wapiti  has  only  been  observed  in  a  fossil  state  in 
Pleistocene  deposits.  We  know  from  these  records  that  its 
range  extended  in  Pleistocene  times  southward  as  far  as 
Florida  and  from  North  Carolina  to  New  Jersey  and  Kentucky. 

The  resemblance  between  the  American  wapiti  and,  at  any 

*  Lydekker,  E.,  "  Catalogue  of  Fossil  Mammalia,"  II. ,  p.  24. 
t  Seton,  Ernest  Thompson,  "Life  Histories  of  Northern  Animals,"  I, 
p.  43. 

F2 


68  ORIGIN   OF  LIFE   IN   AMERICA 

rate,  the  eastern  European  races  of  the  red  deer  is  so  close 
that  Dr.  Caton  *  was  sometimes  at  a  loss  to  discriminate 
between  them.  The  late  Professor  Nehringf  also  drew  atten- 
tion to  the  resemblance  of  certain  fossil  deer  antlers  from 
central  and  eastern  Europe  to  those  of  Cervus  canadensis. 
As  we  proceed  westward  in  Europe  the  distinctive  cha- 
racters of  the  red  deer  become  more  prominent,  and  less  so 
as  we  travel  towards  America  through  Asia.  Dr.  Tcherski,J 
I  think,  was  the  first  to  direct  attention  to  the  fact  that  the 
wapiti  was  a  variety  of  the  Siberian  maral.  And  a  similar 
opinion  has  more  recently  been  expressed  by  Mr.  Lydekker.  § 

It  is  many  years  since  I  argued  that  the  Elaphus  group  of 
the  genus  Cervus,  to  which  the  Canadian  wapiti  and  thie 
European  red  deer  belong,  originated  in  Central  Asia,  and 
I  have  not  had  any  cause  to  modify  my  views  in  this  respect.  || 

Cervus  canadensis  differs  from  all  other  American  deer  and 
agrees  with  the  great  majority  of  the  Old  World  forms  in  so 
far  as  the  proximal  portions  of  the  lateral  metacarpal  bones 
persist.  This  is,  as  Sir  Victor  Brooke  first  pointed  out,  an 
important  structural  character.  In  the  possession  of  these 
small  leg-bones  the  Canadian  wapiti  stands  entirely  apart 
from  its  more  distant  relations  of  the  American  Continent, 
while  clearly  betraying  its  close  relationship  to  the  Siberian 
maral  and  the  Old  World  deer  generally.  Its  presence  in 
America,  therefore,  forms  one  of  the  most  powerful  argu- 
ments in  favour  of  the  view  that  North  America  and  Asia 
have  been  united  by  land  within  fairly  recent  geological 
times.  We  shall  meet  with  so  many  similar  examples  during 
the  course  of  this  work,  that  one  might  almost  be  inclined  to 
say  that  the  matter  requires  no  further  proof,  that  it  is  an 
established  fact.  Notwithstanding,  one  of  the  most  distin- 
guished authorities  in  America  is  not  disposed  to  accept  the 
view  that  there  was  such  a  recent  land  connection.  Nor  is 
it  expedient  for  us  to  adopt  the  attitude  of  the  modern 
glacialist  who,  in  referring  to  the  theory  of  the  presence  of 

*  Caton,  J.  D.,  "Antelope  and  Deer  of  America,"  p.  214. 

t  Nehring,  A.,  "  Tundren  und  Steppen,"  p.  203. 

\  Tcherski,  J.  D.,  "  Das  Janaland,  &c.,"  p.  496. 

§  Lydekker,  E.,  "  Geographical  History  of  Mammals,"  p.  315. 

'I  Scharft',  R.  F.,  "  Mammiferes  de  la  region  holarctique,"  p.  448. 


ORIGIN   OF   WAPITI  DEER  69 

gigantic  glaciers  during  the  Ice  Age,  exclaims  "  this  is  no 
vain  hypothesis  or  speculation  founded  on  uncertain  data, 
no  mere  conjecture  which  the  light  of  future  discoveries  may 
explode.  The  evidence  is  so  clear  and  so  overwhelmingly 
convincing  that  we  cannot  resist  the  inevitable  conclusion."* 

The  Canadian  wapiti  deer  is  a  typical  example  of  a  recent 
Asiatic  immigrant.  In  some  previous  cases  it  was  doubtful 
whether  the  species  referred  to  was  of  truly  American  or 
Asiatic  origin.  Again  in  others  we  were  able  to  trace  a 
distinctly  American  ancestry,  but  not  beyond  the  more  recent 
deposits. 

I  want  now  to  mention  an  interesting  creature  whose 
lineage  we  can  follow  through  several  geological  ages,  and 
whose  most  remote  ancestors  had,  as  we  might  say,  not 
a  drop  of  foreign  blood  in  their  veins.  The  species  I  allude 
to  is  the  Canadian  tree  porcupine  (Erethizon  dorsatus).  It 
is  in  many  respects  a  most  striking  and  remarkable  animal. 

In  Europe,  in  fact  everywhere  in  the  Old  World,  porcu- 
pines are  ground  animals,  and  they  usually  dig  their 
burrows  in  the  earth.  The  American  porcupines  differ  from 
them  in  many  important  anatomical  characters.  They,  more- 
over, all  live  on  trees,  and  generally  have  prehensile  tails. 
We  have  here  two  entirely  distinct  groups,  as  among  the  deer, 
though  externally  all  porcupines  have  a  strong  family  like- 
ness. As  far  as  trees  grow  right  up  to  the  barren-grounds  the 
Canadian  porcupine  was  once  abundant,  but  yielding  whole- 
some food  and  being  easily  killed  it  has  been  exterminated  in 
many  districts.  Whenever  it  is  undisturbed  it  is  plentiful,  feed- 
ing on  leaves  and  bark,  and  it  seems  entirely  unaffected  by 
climatic  extremes.  The  Canadian  tree  porcupine  lives  in 
Canada  from  the  Rocky  Mountains  in  the  west  to  southern 
Labrador  in  the  east,  and  enters  the  United  States  in  Maine 
and  New  Hampshire.  Formerly  it  occurred  all  along  the 
Alleghenies,  through  Pennsylvania  into  Virginia  and  Ken- 
tucky to  Arkansas.  In  these  southern  parts  of  its  range  it 
no  doubt  fell  an  easy  prey  to  the  Indian  hunters  who  were 
always  fond  of  its  flesh.  The  destruction  of  forests  on  the 
arrival  of  the  white  man  hastened  its  northward  retreat. 

*  Geikie,  James,  "The  Great  Ice  Age,"  pp.  67—68. 


70  OKIGIN   OF   LIFE   IN   AMEEICA 

There  is  no  sign  here  of  a  post-Glacial  centre  of  dispersal 
south  of  the  drift  area.  The  centre  of  dispersal,  on  the  con- 
trary, lies  in  Canada  and  it  is  from  there  that  it  has  spread 
southward.  Yet  the  species  had  already  come  into  existence 
when  the  sabre-tooth  tiger  and  peculiar  kinds  of  peccaries 
haunted  the  forests  of  Arkansas,  for  its  remains  have  been 
found  together  with  these  extinct  creatures  in  the  Conard 
fissure.*  It  likewise  lived  in  Pennsylvania  at  a  time  when 
the  great  Mylodon,  Megalonyx  and  Mastodon  still  flourished 
there. 

Beyond  the  Mackenzie  Eegion,  in  the  far  distant  Alaska, 
there  lives  another  porcupine  very  closely  related  to  the 
Canadian  species.  This  yellow-haired  porcupine  (Erethizon 
epixanthum),  as  it  is  called,  ranges  from  Alaska  through 
the  Eocky  Mountains  and  westward  to  the  Pacific  as  far  south 
as  northern  Mexico,  thus  exhibiting  the  same  indifference 
to  climatic  conditions  as  its  near  relative.  Both  of  these 
North  American  porcupines  have  short  tails.  In  Mexico, 
Central  and  South  America  we  meet  with  numerous  species, 
all  allied  to  Erethizon,  but  with  prehensile  tails,  which 
considerably  assist  them  in  climbing  trees. 

Now  if  the  genus  to  which  these  tree  porcupines  belong  had 
originated  in  Alaska  or  Canada,  we  should  certainly  expect 
it  to  have  traversed  Bering  Strait  into  Asia  while  the  wapiti 
deer  and  many  other  Old  World  forms  poured  into  America. 
That  it  has  not  done  so  does  not  tend  to  disprove  the  assump- 
tion of  the  former  existence  of  a  Bering  Strait  land  bridge. 
It  only  implies  that  the  genus  Erethizon  is  of  southern 
origin,  and  has  merely  spread  northward  within  recent  geo- 
logical times.  The  south-western  region,  that  vast  country 
of  mountains  and  plains  which  contains  the  most  important 
centre  of  dispersal  in  North  America,  has  no  doubt  given 
rise  to  the  genus  Erethizon.  Of  its  past  history  we  know 
nothing  as  far  as  North  America  is  concerned.  South  of 
Mexico,  as  already  stated,  all  tree  porcupines  possess  pre- 
hensile tails,  and  are  distinguished  by  other  minor  differ- 
ences from  Erethizon.  For  these  reasons  they  have  been 
placed  into  the  distinct  genus  Coendu.  These  southern  forms 

*  Brown,  Barnum,  "Conard  Fissure,"  p.  166, 


CANADIAN   TREE   PORCUPINE  71 

of  tree  porcupines  have  apparently  advanced  northward  along 
the  isthmus  of  Central  America  and  have  reached  Mexico 
within  quite  recent  times.  There  are  no  grounds,  however, 
for  the  supposition  that  Erethizon  is  a  modified  Coendu. 
When  North  and  South  America  became  joined  by  the  exist- 
ing isthmus  of  Central  America  in  Pliocene  times,  Erethizon 
no  doubt  was  already  an  inhabitant  of  the  northern  continent. 
Since  the  two  genera  belong  to  the  same  family  Coendidae, 
which  differs  fundamentally  from  the  Old  World  family 
Hystricidae,  we  must  assume  that  long  anterior  to  the  Plio- 
cene Period  North  and  South  America,  or  such  portions  of 
those  continents  which  then  existed,  had  already  been  united 
and  then  become  disconnected  again.  These  theories  ,are 
not  founded  on  zoogeographical  data  alone.  Professor 
Osborn  *  urges  on  palaeontological  grounds  that  North  and 
South  America  were  joined  in  Cretaceous  and  perhaps  in 
early  Tertiary  times,  and  then  separated  again  until  the 
Pliocene. 

All  this  will  be  discussed  in  detail  when  we  come  to  deal 
with  Central  America.  I  only  mention  the  matter  now 
because  in  the  Santa  Cruz  beds  of  Patagonia  the  skeleton  of 
a  peculiar  tree  porcupine  has  been  discovered  and  placed 
by  Dr.  Ameghino  into  the  new  genus  "  Steiromys."  More 
recently,  Professor  W.  B.  Scottf  re-examined  these  Steiromys 
remains,  and  noted  the  remarkable  fact  that  they  are  more 
like  the  recent  Erethizon  of  North  America  than  any  of  the 
modern  South  American  tree  porcupines.  He  even  argues 
that  Steiromys  is  the  direct  ancestor  of  Erethizon. 

As  this  implies  a  former  land  connection  between  Pata- 
gonia and  North  America,  independently  of  the  remainder 
of  South  America,  it  largely  aided  me  in  the  theoretical 
construction  of  an  ancient  land  bridge  between  south.- western 
North  America  and  Chile.  J  It  is  on  this  land  bridge,  I  think, 
that  the  ancestor  of  the  North  American  Erethizo-n  wandered 
northward  from  Patagonia  in  early  Tertiary  times.  All  this 
will  be  more  fully  explained  later  on. 

*  Osborn,  H.  F.,  "Progress in  Mammalian  Palaeontology,"  p.  99. 
t  Scott,  W.  B.,  "  Eeport  of  Princeton  Expedition,"  V.,  pp.  413—417. 
{  Scharff,  E.  F.,  "  Early  Tertiary  Land-Connection,"  p.  521, 


72  OEIGIN   OF   LIFE   IN   AMERICA 

It  may  be  of  interest  now  to  inquire  as  to  how  far  a  group 
of  loss  mobile  creatures  than  the  mammals,  the  snails,  for 
instance,  can  be  classified  into  species  whose  ancestors  were 
Asiatic,  and  such  as  were  originally  native  to  the  soil.  Of 
course  we  need  only  consider  snails  resident  in  the  Atha- 
baska — Mackenzie  Region.  A  direct  European  influence 
among  the  fresh -water  molluscan  fauna  is  apparent,  since 
certain  species  such  as  Limnaea  stagnalis,  L.  truncatula,  L. 
palustris,  and  Aplexa  hypnorum  inhabit  the  Mackenzie 
Region  as  well  as  Europe.  How  they  have  spread  to  America 
is  not  readily  ascertainable.  The  points  of  resemblance 
between  the  two  regions  are  clearly  of  long  standing,  but  none 
of  these  species  need  necessarily  have  come  from  Europe 
direct,  as  they  all  inhabit  Siberia  as  well  as  Canada. 

Among  the  land  snails  we  also  meet  with  forms  familiar 
to  the  European  conchologist,  such  as  Pupa  muscorum, 
Cochlicopa  lubrica,  Hyalinia  radiatula,  H.  nitidula,  Euconu- 
lus  fulvus,  Zonitoides  nitidus,  and  others.  All  these  are  no 
doubt  very  ancient  species,  too  ancient  in  fact  to  help  us 
materially  in  our  present  inquiries*  It  is  possible,  moreover, 
that  they  have  special  facilities  for  accidental  dispersal,  that 
is  to  say  for  dispersal  other  than  the  ordinary  mode  of  pro- 
gression on  land,  although  my  studies  have  not  led  me  'to 
believe  in  the  efficacy  of  such  a  mode  of  conveyance  in 
permanently  stocking  a  country. 

The  strictly  American  Pupa  armifera  and  P.  holzingeri, 
Vertigo  ventricosa,  V.  ovata,  Vitrina  limpida,  Patula  solitaria, 
and  P.  striatella  are  all  easily  transported  by  flooded  streams, 
and  thus  scattered  far  and  wide.  In  spite  of  the  fact  that  the 
land  and  fresh-water  mollusks  of  the  Mackenzie  Region 
indicate  that  a  distinct  Old  World  influence  is  recognisable, 
nothing  points  definitely  to  a  recent  land  connection  with 
either  Europe  or,  Asia.  They  do  not  confirm  the  view  that  any 
survival  of  the  molluscan  fauna  through  the  Glacial  Epoch 
has  taken  place  in  that  region.  On  the  contrary,  the  absence 
of  species  peculiar  to  the  region  implies,  as  among  the 
mammals,  that  that  part  of  America  has  only  recently  been 
stocked  with  animals  from  another  portion  of  the  continent. 
Whether  we  assume  that  gigantic  glaciers  covered  the  coun- 
try, or  whether  we  argue  that  the  ocean  invaded  it,  the, 


SNAILS   OF   THE   NORTH  WEST  73 

ultimate  effect  would  be  somewhat  similar.  In  reality  it 
would  not  be  quite  the  same,  because  in  the  latter  case  it  is 
conceivable  that  the  whole  Rocky  Mountain  chain,  which  lay 
to  the  west  of  the  flooded  territory,  could  have  supported  a 
fairly  rich  fauna  and  flora.  If  a  huge  glacier  really  existed 
in  the  Keewatin  district,  it  is  inconceivable  to  suppose  that 
any  but  the  most  scanty  fauna  and  flora  could  have  found  a 
stray  asylum  on  the  few  isolated  "  Nunatakkr  "  projecting 
beyond  the  Rocky  Mountain  ice-fields. 

The  mollusks  do  not  favour  either  theory.  The  mammals, 
on  the  other  hand,  show  clearly  a  geologically  recent  invasion 
of  Old  World  forms  from  the  west,  which  is  more  compatible 
with  what  I  may  call  the  marine  theory. 

Mr.  Walker  *  contends  that  the  Glacial  Epoch  was  a  great 
factor  influencing  the  distribution  of  the  North  American 
molluscan  fauna.  I  can  only  perceive  signs  of  local  destruc- 
tion. The  distribution  of  the  land  and  fresh -water  mollusks 
in  North  America  took  place  evidently  long  before  this  Glacial 
Epoch,  and  was  not  seriously  influenced  by  the  latter. 

Both  theories  will  be  more  fully  dealt  with  in  the  next 
chapters  in  which  the  animals,  principally  of  Alaska,  will  be 
described.  These  animals  afford  us  more  material  for  our 
inquiries,  being  of  great  importance  to  the  just  appreciation 
and  understanding  of  the  varied  origin  and  development  of 
the  American  fauna. 

*  Walker,  Bryant,  "  Origin  and:  Distribution  of  Mollusca,"  p.  53. 


CHAPTER  IV 


THE    FAUNA    OF    ALASKA 

SINCE  Alaska  came  into  the  possession  of  the  United  States 
its  progress  has  been  a  rapid  one.  The  sudden  development 
of  the  resources  of  this  vast  country  attracted  public  atten- 
tion and  led  to  urgent  demands  for  further  exploration  of  its 
natural  wealth.  This  work  has  been  actively  prosecuted 
within  the  last  few  years,  so  that  we  now  possess  some  know- 
ledge of  the  geography,  geology  and  mineral  resources  of  the 
country.  Situated  in  the  north-westerly  extremity  of  North' 
America,  its  area  equals  in  size  about  one  fifth  of  the  United 
States  (see  Fig.  1).  It  is  nearly  three  times  as  large  as  the 
German  Empire. 

A  broad  mountain  belt  spreads  along  the  Pacific  coast  of 
Alaska,  its  western  prolongation  being  still  recognisable  in  the 
chain  of  the  Aleutian  Islands.  The  north-eastern  extension  of 
the  Eocky  Mountains  curves  rapidly  westward  on  reaching  the 
Arctic  Ocean  and  there  forms  a  range  almost  parallel  with  the 
north  coast  of  Alaska.  Between  these  two  mountain  systems 
lies  partly  a  plateau  and  partly  a  great  plain  drained  by  the 
Yukon  Kiver,  the  latter  sending  its  waters  into  the  Bering 
Sea.  About  one  quarter  of  Alaska  lies  within  the  Arctic 
Circle.  Hence,  from  the  standpoint  of  geographic  position, 
it  must  be  regarded  as  an  Arctic  province.  The  southern 
sea-board,  on  the  other  hand,  which  is  exposed  to  the  warm 
winds  and  waters  of  the  Pacific  Ocean,  gives  a  comparatively 
mild  climate  to  the  entire  southern  portion  of  the  territory. 
Thus  Dr.  Brooks  *  draws  attention  to  the  fact,  which  few  of 
us  probably  realize,  that  the  range  of  climate  in  Alaska  is 
greater  than  that  between  Maine  and  Florida. 

The  capital  of  the  country,  Sitka,  has  a  slightly  lower  mean 

*  Brooks,  A.  H.,  "  Geography  and  Geology  of  Alaska,"  p,  11. 


GLACIEKS   AND  VOLCANOES  75 

temperature  than  Scotland,  but  it  has  a  much  greater  rain- 
fall. This  enormous  precipitation  on  the  Pacific  coast  has 
a  striking  effect  on  the  vegetation.  The  whole  of  south-eastern 
Alaska  is  densely  timbered  with  forests  of  spruce  and  hem- 
lock, also  red  and  yellow  cedar  and  other  trees,  their  luxurious 
growth  contrasting  strongly  with  the  open  forests  of  the 
interior  and  the  more  northern  treeless  barren-grounds.  Yet 
the  lowlands  of  the  interior  are  usually  well  wooded  with 
spruce,  cottonwood,  birch,  willow  and  alder.  At  a  height  of 
from  about  2,000  to  3,000  feet  above  sea-level,  forest  growth 
ceases  altogether.  Here  the  climate  becomes  continental  in 
character,  with  great  extremes  of  heat  and  cold.  In  the 
northern  parts  of  the  country  the  surface  everywhere  is 
covered  with  dense  growth  of  moss  and  grass,  with  an 
abundance  of  wild  flowers,  whereas  the  ground  beneath  is 
perpetually  frozen. 

Alaska  possesses  many  other  features  of  unrivalled  interest. 
The  magnificent  peaks  clustering  about  Mount  Fairweather 
as  a  centre,  and  containing  Mount  St.  Ellas,  Mount  Logan 
and  Mount  McKinley,  the  latter  with  a  height  of  20,400 
feet  being  the  loftiest  mountain  in  North  America,  have 
excited  the  just  admiration  of  those  who  have  been  fortunate 
enough  to  visit  this  region.  Splendid  glaciers  here  and  there 
descend  from  the  great  mountain  valleys  down  to  sea-level, 
while  further  west  we  notice  in  Mount  Wrangell  a  fine  example 
of  an  active  volcano.  The  vast  glaciers  have  given  rise  to 
the  popular  idea  that  Alaska  is  a  country  of  unlimited  snow 
and  ice.  As  a  matter  of  fact  they  are  almost  entirely  confined 
to  the  Pacific  mountain  system. 

Near  the  sea  border  the  climate  is,  as  I  mentioned,  much 
milder  than  in  the  interior  of  the  country,  yet  an  abundant 
precipitation  from  the  warm  moisture -laden  winds  here  pro- 
duces the  extensive  snow-fields  from  which  the  glaciers  are 
fed.  On  the  land  side  of  the  Pacific  Mountain  range  glaciers 
are  very  poorly  developed.  Further  inland  they  are  entirely 
absent. 

Since  a  vast  area  of  land  in  Alaska  remains  uncovered  by 
ice,  in  spite  of  a  low  mean  temperature,  we  must  recognise  the 
justice  of  Professor  Whitney's  assertion,  that  a  still  greater 
increase  of  cold  would  not  cover  those  regions  with  ice,  nor 


76  ORIGIN   OF   LIFE   IN   AMERICA 

bring  about  the  conditions  of  a  Glacial  Epoch.  On  the  con- 
trary, it  is  evident  that  the  opposite  result  would  take  place. 
The  conditions  of  a  Glacial  Epoch,  says  Professor  Whitney, 
are  not  to  be  sought  for  in  a  general  diminution  of  tem- 
perature. "  It  is  true,"  he  argues,  "  that  the  regions  in  which 
the  glaciers  take  their  rise  cannot  be  so  warm  that  precipita  - 
tion  takes  the  form  of  rain ;  but  the  required  low  temperature 
must  be  confined  to  a  limited  area,  and  be  brought  about  by 
local  causes,  and  not  be  something  in  which  all  the  other 
portions  of  the  earth  are  sharers.  There  must  be  copious 
precipitation,  which,  although  locally  in  the  form  of  snow, 
can  in  reality  only  be  the  result  of  a  high  mean  temperature 
in  other  regions.  In  short,  warmth,  as  a  phenomenon  of 
general  occurrence,  is  more  indispensably  necessary  than  cold, 
because  the  latter  may  always  be  produced,  where  locally 
wanted,  by  increase  of  elevation  or  by  the  shifting  of  the 
ocean  currents."* 

We  now  know  that  the  glaciation  of  Alaska  during  the 
Ice  Age  must  be  regarded  as  an  extension  of  the  present 
system  of  glaciers.  They  were  no  doubt  considerably  larger, 
while  glaciers  also  existed  in  the  Endicott  range  in  north- 
western Alaska.  Nevertheless,  no  signs  of  former  glaciation 
have  as  yet  been  discovered  in  the  interior  of  the  country. 
The  latter  is  now  generally  believed  to  have  been  entirely 
unglaciated.  If  we  adopted  Professor  Whitney's  views,  and 
endeavoured  to  picture  to  ourselves  the  conditions  of  Alaska  in 
the  Glacial  Epoch,  we  must  imagine  the  Pacific  to  have  been 
warmer  than  it  is  now  and  the  climate  of  Alaska  much  milder 
and  more  humid.  A  more  luxuriant  flora  would,  under  such 
circumstances,  have  been  able  to  flourish  in  the  interior  of  the 
country,  and  consequently  a  richer  and  more  varied  fauna. 

And  how  much  is  this  conception  of  the  Glacial  Epoch  at 
variance  with  the  theories  generally  propounded !  I  may  be 
excused,  for  example,  for  again  citing  Professors  Chamberlin 
and  Salisbury's  f  words,  that  one  of  the  most  marvellous 
features  of  the  ice-dispersion  during  the  Glacial  Epoch  was 

*  Whitney,  J.  D.,  "Climatic  Changes,"  p.  388. 

t  Chamberlin,  T.  C.,   and  E.  D.  Salisbury,   "Geology,"   Vol.   III. 
pp.  332—333. 


ALASKA   DURING  ICE  AGE  77 

the  pushing  out  of  the  Keewatin  ice-sheet  from  a  low  flat 
centre,  without  even  a  suggestion  of  a  mountainous  nucleus, 
to  one  thousand  miles  westward,  while  the  Rocky  Mountain 
glaciers  were  thrust  eastward,  but  little  beyond  the  foot- 
hills. 

The  ice  from  this  great  centre  of  dispersion  is  supposed 
to  have  reached  the  mouth  of  the  Mackenzie  River  close  to 
the  borders  of  Alaska.  Nevertheless,  the  same  authors  ac- 
knowledge that  the  plains  of  Alaska  were  apparently  free  from 
glaciation,  even  during  the  time  when,  two  thousand  miles 
further  south,  the  waters  of  the  Ohio  and  the  Missouri  were 
actually  believed  to  have  been  turned  from  their  courses  by  the 
encroaching  ice-sheets.  How  can  we  reconcile  the  co-existenoe 
of  these  two  extraordinary  and  altogether  anomalous  climatic 
conditions  in  adjoining  parts  of  the  same  continent  ?  Surely 
there  must  be  some  mistake.  At  present  there  is  far  less  pre- 
cipitation of  moisture  in  the  Keewatin  region  of  Canada  than 
in  any  of  the  western  mountain  ranges.  The  existing  con- 
ditions of  land  and  water  must  consequently  have  been  entirely 
altered  during  the  Glacial  Epoch.  Indeed,  even  our  concep- 
tions of  the  nature  of  climates  would  have  to  undergo  some 
change  [before  we  can  realize  how  this  stupendous  ice -sheet 
in  the  Keewatin  region  came  to  be  built  up,  while  Alaska  was 
only  able  to  form  a  few  local  glaciers.  In  a  previous  chapter 
(p.  46)  I  ventured  to  make  some  critical  remarks  on  the 
supposed  gigantic  ice-sheets  of  the  Glacial  Epoch,  and  I  hope 
to  show  now  that  the  biological  evidences  are  altogether  op- 
posed to  the  views  that  the  Ice  Age  was  an  epoch  of  excep- 
tional cold.  My  criticisms  on  the  current  beliefs  in  the  land- 
ice  theory  are  by  no  means  new.  We  need  only  peruse  the 
fascinating  volumes  entitled  "  Ice  or  Water  "  published  by 
Sir.  Henry  Howorth,  in  which  the  claims  of  water  as  a  power- 
ful agent  in  the  formation  of  so-called  glacial  deposits  are 
ably  discussed.  My  object,  however,  in  writing  this  work  was 
not  to  investigate  the  origin  of  the  Ice  Age.  This  short 
digression  into  the  domain  of  glacial  geology  merely  serves 
to  acquaint  the  general  reader  with  s,ome  of  the  special 
difficulties  we  have  to  contend  with  in  explaining  certain 
phenomena  connected  with  the  Alaskan  fauna. 

Since  the  beginning  of  the  last  century  it  was  known  that 


78  ORIGIN  ?OF   LIFE   IN   AMEEICA 

fossil  ivory  might  be  gathered  on  the  shores  of  Alaska. 
Several  Kussian  authorities  reported  on  its  occurrence  there, 
animadverting  to  the  fact  that  the  remains  of  elephants  had 
also  been  discovered  on  some  of  the  Pribilof  Islands.  Within 
recent  years  several  expeditions  have  been  sent  to  Alaska 
from  the  United  States  with  a  view  to  discovering  more  about 
these  and  other  remains  of  extinct  animals.  The  first  of  these 
was  dispatched  by  the  Smithsonian  Institution  of  Washington 
in  1904.  Mr.  Maddren,  who  had  already  visited  the  country 
several  times  and  had  travelled  extensively  in  the  interior, 
was  charged  with  the  expedition,  and  he  issued  an  interesting 
report  on  his  return. 

He  contends  that  the  lowest  beds  in  Alaska  in  which- 
mammoth  remains  occur  are  the  "  lacustrine  silts,"  which' 
form  an  extensively  developed  feature  in  the  country. 
Scattered  through  these  Pleistocene  deposits  we  find  remains 
of  skeletons,  isolated  cheek-teeth,  tusks  and  bones,  the  animals 
to  which  they  belonged  having  probably  died  near  the  shores 
of  the  lakes  in  the  bottom  of  which  they  became  embedded. 
These  fluvial  and  lacustrine  beds  of  Alaska,  with  their  occa- 
sional gravels,  rest  unconformably  on  the  eroded  surfaces 
of  the  .older  formations.  At  the  time  the  silts  and  clays  were 
forming  Alaska  was  for  the  most  part,  according  to  Mr. 
Maddren,*  a  low -lying  country,  characterised  by  enlarged 
rivers  with  slow  drainage,  and  many  lakes. 

The  general  conclusions  arrived  at  by  Mr.  Maddren  are, 
"  that  while  remnants  of  the  large  Pleistocene  mammal  herds 
may  have  survived  down  to  the  recent  period,  and  in  some 
cases  their  direct  descendants,  such  as  the  musk  ox,  have 
done  so,  most  of  them  became  extinct  in  Alaska  with  the  close 
of  the  Pleistocene.  The  most  rational  way  of  explaining  this 
extinction  of  animal  life,  says  Mr.  Maddren,  is  by  a  gradual 
alteration  of  the  climate  from  more  temperate  conditions,  per- 
mitting of  a  forest  vegetation  much  further  north  than  now, 
to  the  more  severe  climate  of  to-day.  Recent  changes,  while 
checking  the  vegetation  and  thus  reducing  the  food  supply, 
have  acted  injuriously  on  animal  life,  only  leaving  those 
forms  that  were  capable  of  adapting  themselves  to  the  new 

*  Maddren,  A.  G.,  "  Smithsonian  Exploration  in  Alaska,"  pp.  25-^28. 


EXTINCT   MAMMALS  OF  ALASKA  79 

conditions.  Mr.  Maddren  urges  that  there  are  no  facts  to  sup- 
port the  contention  that  the  climates  of  the  Arctic  and 
sub-Arctic  regions  ever  had  been  colder  than  they  are  at 
present.  He  thinks  that  there  are  no  phenomena  presented 
by  the  past  history  of  these  regions  that  require  a  more 
severe  climate  than  that  now  existing  to  account  for  them. 
There  are  no  ice  deposits  in  Alaska,  he  says,  except  those  of 
large  glaciers,  that  may  be  considered  of  Pleistocene  age. 
There  are  no  ice-beds,  he  continues,  interstratified  with  the 
Pleistocene  deposits  of  Alaska.  Finally  he  argues  that  the 
various  forms  of  land  ice,  together  with  the  deposits  of  peat, 
now  existing  throughout  the  Arctic  and  sub -Arctic  regions 
of  Alaska,  belong  to  the  Eecent  Period,  and  that  these  deposits 
may  be  most  conveniently  and  logically  classified  by  their 
position  with  reference  to  the  Pleistocene  and  Keeent  forma- 
tions, and  that  the  ice  deposits  cannot  be  differentiated  satis- 
factorily into  deposits  of  snow  or  water  origin  by  their 
physical  structure  and  character  alone.* 

A  second  Smithsonian  expedition  to  Alaska  was  dispatched 
a  few  years  later  under  Mr.  Gilmore.  He  noticed  that  the 
scattered  remains  of  Pleistocene  animals  occurred  throughout 
the  unglaciated  region  of  Alaska  and  the  adjacent  Canadian 
territory  in  three  distinct  deposits,  viz.,  in  what  is  locally 
known  as  "  black  muck,"  which  is  accumulated  in  the  valleys 
of  the  smaller  streams,  then  in  the  silt  and  clays  already 
referred  to,  and  finally  in  the  more  recent  fluvial  and  alluvial 
beds.  The  best-preserved  remains  were  obtained  in  the  muck 
deposits,  and  in  these  occurred  certainly  several  examples  of 
primary  entombment.  A  magnificent  skull  with  tusks  of  the 
mammoth  was  discovered  in  the  muck  forty-two  feet  below 
the  surface,  near  Dawson,  in  the  Yukon  territory  in  north- 
western Canada.  Mr.  Gilmore  f  is  -convinced  that  the 
determinable  species  of  mammals  found  are  sufficient  to 
show  at  once  that  they  represent  a  typical  Pleistocene 
fauna,  some  of  them,  such  as  the  moose,  caribou,  musk  ox, 
sheep,  bear,  and  beaver,  having  persisted  down  to  the  present 
day. 

*  Maddren,  A.  G.,  "  Smithsonian  Exploration  in  Alaska,"  pp.  65 — 66. 
t  Gilmore,  C.  W.,  "Smithsonian  Exploration  in  Alaska,"  pp.  26—38. 


80  OEIGIN  OF  LIFE  IN  AMERICA 

The  complete  list  of  mammals  is  as  follows : — 

Mammoth      (Elephas  primi-      Extinct      musk     ox       (Symbos- 

genius).  tyrelli). 

Mastodon     (Mastodon  ameri-      Bison  (Bison  crassicornis). 

canus).  „     (Bison  occidentalis). 

Horse  (Equus  sp.).  ,,     (Bison  alleni). 

Moose  (Alces  sp.).  Sheep  (Ovis  sp.). 

Reindeer  (Rangifer  sp.).  Bear  (Ursus  sp.). 

Musk  ox  (Ovibos  sp.).  Beaver  (Castor  sp.) 

The  results  of  these  two  expeditions  excited  so  much  interest 
in  the  United  States  that  another  was  sent  out  to  Alaska  by 
the  American  Museum  of  Natural  History  under  Mr. 
Quackenbush.*  He  was  fortunate  enough  in  discovering  part 
of  a  mammoth  skeleton  which  still  retained  the  flesh,  skin 
and  hair  similar  to  those  found  in  northern  Siberia.  This 
discovery  is  of  particular  interest,  as  it  elucidates  an  extremely, 
important  feature  connected  with  the  preservation  of  the  soft 
parts  of  mammoths  in  Siberia.  It  has  been  stated  that  the 
preservation  of  the  bodies  of  mammoths  is  due  to  their  being 
embedded  in  underground  ice.  Mr.  Gilmore  informs  us  that 
fossils  in  Alaska  have  never  been  found  in  pure  ice  masses. 
On  the  contrary,  he  makes  it  quite  clear  that  the  flesh,  skin 
and  hair  of  the  mammoth  were  preserved  to  the  present  time 
because  they  had  been  pressed  down  into  the  soft  mud  by  the 
weight  of  the  rest  of  the^body.  All  that  remained  exposed 
of  the  hody  rotted  away  ./The  author  agrees  with  the  previous 
writers  in  considering  uie  mammoth  and  the  mammalian  re- 
mains as  Pleistocene.  He  argues  that  the  climate  of  this 
period  must  have  been  somewhat  milder  than  that  of  the 
present  time,  because  large  trees  had  been  met  with  associated 
with  these  mairdnalian  remains  in  regions  which  are  now  tree- 
less. He  also  adds  Bootherium  bombifrons,  the  wapiti  deer 
and  the  wolf  to  the  Pleistocene  species  already  known  from 
the  Yukon  territory  of  Canada. 

From  these  three  most  valuable  reports  we  can  gather  cer- 
tain remarkable  facts  which  are  apparently  antagonistic  to 

*  Quackenbush,  L.  S.,  "Alaskan  Mammoth  Expeditions,"  pp.  125 — 
127. 


FORMER  CLIMATE   OF   ALASKA  81 

the  theory  of  the  existence  of  enormous  ice -sheets  in  dis- 
tricts adjoining  Alaska  during  Pleistocene  times.  All  the 
writers  agree  that  the  numerous  mammals  .whose  remains  were 
discovered  in  Alaska  lived  there  in  the  Ice  Age  during  climatic 
conditions  w'hich  were  vastly  more  favourable  than  those  now 
prevailing.  Evidences  of  a  milder  climate  are  furnished  by 
the  abundance  of  mammoth  remains  in  Alaska.  Horses,  rein- 
deer and  herds  of  bisons  likewise  roamed  all  over  the  country. 
Hence  rich  meadows  and  forests  mus^b  have  been  plentiful 
to  support  them  all  with  food.  Nothing  whatsoever  has  been 
brought  to  light  which  would  sustain  the  theory  expressed 
by  some  writers  that  this  fauna  inhabited  Alaska  during  a 
mild  post-Glacial  or  inter-Glacial  stage.  No  trace  of  the  exist- 
ence in  Alaska  of  a  cold  period  preceding  the  supposed  inter- 
Glacial  or  post-Glacial  stage  has  been  found.  We  must  con- 
clude, therefore,  that  Alaska  and  the  neighbouring  countries 
during  the  whole  of  the  Pleistocene  Period  had  a  temperate 
climate. 

These  heterodox  views  on  the  climate  during  the  so- 
called  Ice  Age  are  not  new.  They  were  enunciated  by 
Sir  Henry  Howorth  and  supported  by  able  arguments 
more  than  twenty  years  ago.  Very  little  was  then  known 
of  Alaska,  but  the  remains  of  innumerable  large  mammals 
had  been  unearthed  in  northern  Siberia  and  even  on  the  New 
Siberian  Islands  situated  in  the  Arctic  Ocean.  These  dis- 
closures naturally  caused  a  good  deal  of  speculation.  They 
led  to  the  conclusion  that  the  cold  of  the  Ice  Age  or  Glacial 
Epoch  was  succeeded  by  a  warm  or  temperate  climate  during 
which  these  animals  were  tempted  to  wander  into  the  Arctic 
Regions.  After  carefully  examining  the  problem,  however, 
Sir  Henry  Howorth  *  expressed  the  conviction  that  this  mild 
or  temperate  epoch  did  not  follow  the  Ice  Age,  but  pre- 
vailed during  the  whole  of  it.  The  creatures  alluded  to  must, 
therefore,  have  lived  in  those  northern  regions  during  the 
Pleistocene  Period,  which  was  temperate  in  character.  Since 
the  close  of  that  period  Siberia  has  gradually  become  more 
and  more  inhospitable. 

A  few  years  later  the  extremely  valuable  scientific  results  of 

*  Howorth,  H.  H.,  "  Mammoth  and  the  Flood,"  p.  265. 
L.A.  G 


82  ORIGIN    OF   LIFE   IN   AMERICA 

Dr.  Tcherski's  *  expedition  to  the  New  Siberian  Islands  were 
published  by  the  Academy  of  Sciences  in  St.  Petersburg  ;  and 
it  is  of  interest  to  note  that  he  arrived  at  conclusions  similar 
to  those  of  Sir  Henry  Howorth.  He  contended  that  the  causes 
which  produced  glaciation  in  Europe  acted  in  quite  a  different 
manner  on  the  conditions  of  life  in  northern  Siberia,  where 
the  climate  remained  as  a  direct  continuation  of  that  pre- 
vailing in  Tertiary  times,  so  that  this  country  had  a  higher 
tejnperature  during  the  Pleistocene  Period  than  obtains  at 
present. 

He  looks  upon  Siberia  as  a  country  in  which  the  processes 
of  general  refrigeration  of  the  northern  hemisphere  and  the 
deterioration  of  the  conditions  of  existence  for  plant  and 
animal  life  during  the  post-Tertiary  Period  took  a  regular 
and  steady  course. 

Baron  von  Toll  concurs  with  Tcherski  and  other  writers  in 
their  opinion  that  the  large  mammals  whose  carcases  and 
skeletons  are  now  unearthed  in  the  extreme  north  of  Siberia 
really  lived  there,  but  he  urges  that  they  did  not  arrive  there 
until  after  the  Glacial  Epoch.  Underground  ice,  as  in  some 
parts  of  Alaska,  is  extensively  met  with  in  northern  Siberia 
and  in  the  New  Siberian  Islands.  Its  occurrence,  according 
to  Baron  von  Toll,  is  due  partly  to  a  recent  origin  in  crevices 
and  lateral  infiltration,  partly  to  a  former  glaciation  of  Siberia, 
the  ice  having  been  preserved  as  "  relict  ice  "  from  the  Glacial 
Epoch.  Being  a  follower  of  those  who  connect  that  period 
with  a  universal  lowering  of  temperature,  his  contention  is 
that  northern  Siberia  enjoyed  a  milder  climate  in  post-Glacial 
times,  and  that  the  mammoth,  horse,  rhinoceros  and  other 
mammals  were  thereby  induced  to  visit  the  shores  of  the  Arctic 
Ocean  and  the  New  Siberian  Islands,  which,  according  to 
Baron  von  Toll,f  were  then  connected  with  Siberia  and  arctic 
America. 

The  mammoth  and  many  other  animals,  as  I  have  indi- 
cated, invaded  America  from  Asia.  Consequently,  if  we  can 
determine  whether  a  land  connection  existed  between  the 
two  continents,  how  long  it  lasted,  and  what  species  made  use 
of  it  in  their  travels,  some  valuable  data  may  be  obtained  as  a 

*  Tcherski,  J.  D.,  "Das  Janaland,"  p.  469. 

t  Toll,  Eduard  von,  "  Die  fossilen  Eislager,"  pp.  80—85. 


ASIATIC   INVADERS   IN   AMERICA  83 

basis  for  discussion  of  some  of  the  problems  referred  to. 
Other  attractive  inquiries,  such  as  the  influence  of  the  Glacial 
Epoch  on  animal  migrations,  might  be  elucidated.  With  the 
climatic  problem  alone  are  connected  so  many  important  geo- 
logical speculations  that  the  subject  is  well  worthy  of  a  most 
careful  scrutiny. 

At  a  meeting  of  the  Biological  Society  of  Washington  about 
ten  years  ago  the  theme  chosen  for  discussion  was  the  sup- 
posed former  land  bridge  between  Asia  and  North  America. 
Dr.  F.  A.  Lucas  spoke  in  favour  of  a  geologically  recent  brief 
land  connection,  and  supported  his  theory  by  the  geographical 
distribution  of  the  wild  sheep  and  the  brown  bears  of  North 
America,  both  of  which  have  their  near  relations  in  Asia. 
He  also  pointed  to  the  remains  of  mammoth  and  bison  in 
Alaska  as  evidence  of  the  same  view.  An  older  land  connec- 
tion, he  thought,  was  indicated  by  the  occurrence  of  a  fossil 
Nemorrhaedus  in  Colorado  and  of  Elephas  columbi.  Dr. 
Theodore  Gill  concurred  with  the  last  speaker,  and  suggested 
that  the  presence  in  America  of  such  species  of  fishes  as  the 
pike  and  Scaphirhynchus  tended  in  favour  of  the  older  land 
connection.  Mr.  F.  V.  Coville  dwelt  upon  the  importance  of 
plants  in  sustaining  the  view  of  a  transient  and  geologically 
recent  land  bridge.  Additional  testimony  in  favour  of  an 
old  land  connection  of  long  duration  was  brought  forward  by 
Dr.  Stejneger.  He  particularly  emphasised  the  occurrence 
in  Asia  and  America  of  the  alligator  and  the  salamander 
Cryptobranchus.  Dr.  W.  H.  Dall  alone  dissented  from  the 
opinions  expressed,  urging  that  such  mammals  as  the 
mammoth  might  have  crossed  over  Bering  Strait  by  an  ice- 
bridge  which  he  thought  might  have  joined  North  America 
and  Asia  during  the  Glacial  Epoch.* 

Dr.  Dall  f  gave  no  reasons  for  his  aversion  to  the  belief 
in  a  geologically  recent  land  connection  between  North 
America  and  Asia ;  although,  in  acknowledging  that  north- 
eastern Asia  and  Alaska  have  certain  species  of  land  and 
fresh -water  mollusks  in  common,  he  recognised  the  intimate 
relationship  existing  between  the  two  areas. 

*  Lucas,  F.  A.,  Th.  Gill,  and  others,  "Former  Land  Connections." 
t  Dall,  W.  H.,    "Mollusk  Fauna  of  Alaska  and  Eastern  Siberia," 
pp.  365—366, 

G2 


84  ORIGIN   OF   LIFE   IN   AMERICA 

The  problem  at  issue  is  obviously  not  to  be  solved  by  the 
application  of  purely  geological  reasoning.  Dr.  Brooks,  in 
his  splendid  contribution  to  the  geology  of  Alaska,  carefully 
avoids  any  discussion  of  a  former  land  connection  with  Asia. 
In  his  brief  statement  that  a  land  bridge  between  Asia  and 
North  America  could  only  have  been  utilised  for  Glacial  or 
post-Glacial  migrations  of  Asiatic  types,  Professor  Suess  * 
does  not  make  us  acquainted  with  the  reasons  for  his  supposi- 
tion that  the  land  connection  did  not  also  exist  in  Pliocene 
times.  He  alludes  to  the  striking  circumstance  that  the 
hypothetical  land  bridge  was  used  apparently  by  Asiatic  types 
only,  and  leaves  us  wondering  why  American  types  should 
not  have  taken  a  similar  advantage  of  pouring  into  Asia. 
That,  however,  is  part  of  the  problem  which  we  must  reserve 
for  a  later  stage  of  the  discussion. 

Dr.  Matthew  f  does  not  share  Professor  Suess'  opinion, 
for  he  indicates  a  wide  land  connection,  and  Professor  Osborn 
follows  him  in  that  respect,  between  North  America  .and! 
north-eastern  Asia  in  the  Bering  Sea  region  in  Oligocene, 
Miocene,  Pliocene  and  Pleistocene  times. 

As  a  rule  the  opinions  of  geologists  on  this  problem  are 
based  on  biological  evidence  alone.  It  is  the  latter,  there- 
fore, that  we  have  to  rely  upon.  Curiously  enough,  Mr. 
Knopf  £  maintains  that  all  the  stratigraphical  testimony  from 
which  conclusions  of  some  positiveness  can  be  drawn,  record 
only  epochs  of  more  widely-spread  submergence  and  in- 
creased separation  of  the  continents,  although  he  recognises 
the  strength  of  the  palaeontological  demands  in  favour  of 
more  or  less  continuous  inter -continental  communications. 
I  shall  endeavour,  now,  to  critically  examine  the  problem 
from  that  point  of  view.  I  have  already  had  several  oppor- 
tunities of  expressing  my  own  views  on  this  subject  (pp.  32 
and  68),  and  these  are  entirely  in  favour  of  a  geologically 
recent  Bering  Strait  land  bridge  (see  Fig.  7).  But  we  require 
to  know  more  than  this.  We  want  evidence  which  will  lead  to 
the  determination  of  the  geological  age  of  the  bridge  and  the 
approximate  date  of  its  beginning  and  end. 

*  Suess,  E.,  •"  Antlitz  der  Erde,"  Vol.  TIL,  p.  764. 

t  Matthew,  W.  D.,  "  Hypothetical  Outlines  of  Continents." 

|  Knopf,  A.,  "  Probable  Tertiary  Land  Connection,"  p.  419. 


ASIATIC   AFFINITIES   OF   ALASKA  85 

Dr.  Allen  *  considers  the  inter-relationship  of  the  boreal 
mammals  inhabiting  North  America  and  northern  Asia  so 
intimate  that  it  could  only  have  been  brought  about  by  the 
existence  of  a  geologically  recent  land  bridge  connecting  the 
two  areas.  He  thinks  that  most  of  the  more  northern  forms 
of  mammal  life  on  the  two  continents  are  probably  the  slightly 
modified  descendants  of  types  which  formerly  had  a  con- 
tinuous circumarctic  distribution,  and  which  have  become 
slowly  differentiated,  mainly,  no  doubt,  since  the  disruption 
of  the  former  land  connection  at  Bering  Strait. 

Every  naturalist  who  casually  surveys  the  boreal  fauna 
of  North  America  and  northern  Asia  must  be  struck  by  the 
apparently  large  predominance  of  Asiatic  invaders  in  North 
America,  such  as  the  moose,  bison,  wapiti  deer,  American 
wild  sheep,  glutton,  brown  bears,  the  now  extinct  mammoth 
and  many  others,  over  the  American  element  in  Asia.  In 
fact,  we  scarcely  recognise  any  signs  of  an  exodus  having, 
taken  place  in  the  opposite  direction.  Typically  American 
mammals,  such  as  the  common  American  musk-rat,  the  por- 
cupine, the  black  bear,  and  others,  for  example,  have  repre- 
sentatives in  Alaska,  nevertheless  they  are  quite  unknown 
on  the  western  shores  of  the  Bering  Sea.  At  the  same  time 
Dr.  Allen  draws  our  attention  to  the  occurrence  along  the 
Siberian  and  Kamchatkan  coasts  of  certain  mammalian  types 
that  are  of  distinctly  American  origin.  These  are  a  species 
of  weasel  (Putorius  pygmaeus)  closely  related  to  the  arctic 
American  weasel  (Putorius  rixosus),  and  only  remotely  akin 
to  any  Eurasiatic  species;  a  spermophile  (Citellus  buxtoni), 
closely  allied  to  the  boreal  American  Citellus  paryi ;  the  Kam- 
chatkan bighorn  (Ovis  nivicola),  which  is  more  nearly  related 
to  American  forms  of  sheep  than  to  Asiatic  ones,  and  several 
others. 

Whether  the  presence  of  these  closely  connected  forms  on 
both  sides  of  Bering  Strait  proves  the  case  of  an  American 
invasion  of  Asia  appears  to  me  still  somewhat  doubtful, 
especially  as  the  sheep  (Ovis)  is,  as  far  as  we  know,  of  Old 
World  origin.  A  sheep  is  known  from  the  Pliocene  Forest 
Bed  of  England,  while  it  only  appeared  in  America  in 

*  Allen,  J.  A.,  "  Mammals  from  North-Eastern  Siberia,"  p.  183. 


86  ORIGIN   OF  LIFE   IN  AMERICA 

Pleistocene  times.  Moreover,  the  Kamchatkan  sheep  (Ovis 
Iiivicola)  is  generally  looked  upon  as  a  very  near  relation 
to  another  Siberian  wild  sheep  also  inhabiting  part  of  Kam- 
chatka, and  which  has  been  found  fossil  by  Tcherski  in  the 
New  Siberian  Islands,  viz.,  Ovis  borealis.  To  judge  by  the 
recent  as  well  as  by  the  fossil  sheep  in  America,  the  genus 
Ovis,  to  which  all  sheep  belong,  must,  I  think,  have  pene- 
trated to  North  America,  together  with  the  mammoth  and 
other  mammals,  in  comparatively  recent  geological  times. 
I  shall  return  to  the  distribution  of  the  American  sheep 
later  on. 

I  should  have  thought  the  genus  to  which  the  musk  ox 
(Ovibos)  belongs  was  a  better  example  of  an  American 
intruder  into  Asia.  Although  no  longer  inhabiting  the  Old 
World,  its  incursions  into  Asia  and  Europe  must  have  taken 
place  about  the  same  time  as  the  mammoth's  advent  in 
America.  A  still  more  striking  instance  of  an  American  in- 
vader into  Asia  is  the  camel,  although  Professor  Osborn's  * 
statement,  "  in  the  Pleistocene  the  camels  wandered  into  Asia 
from  America,  while  the  bears  passed  them  en  route  .toj 
America,"  can  scarcely  be  considered  as  strictly  correct, 
since  two  kinds  of  camels  are  known  from  the  Pliocene 
Siwalik  deposits  of  India.  The  brilliant  researches  of 
American  palaeontologists  have  long  ago  acquainted  us  with 
the  fact  that  the  camel  family  (Camelidae)  inhabited  America 
since  the  dawn  of  the  Tertiary  Era,  while  the  Indian  occur- 
rences alluded  to  are  the  earliest  indications  of  camels  having 
reached  the  Old  World.  It  is  in  Pliocene  times,  therefore, 
or  earlier  even,  that  a  land  connection  between  America  and 
Asia  must  have  existed,  for  no  one  would  venture  to  propound 
the  theory  that  camels  could  have  crossed  from  one  continent 
to  another  on  an  ice  bridge. 

Sir  Henry  Howorthf  collected  in  1892  some  valuable  testi- 
mony showing  that  the  mammoth  had  lived  in  western  Europe 
in  pre-Glacial  times.  In  the  following  year  Dr.  Tcherski  J 
reminded  us  that  a  complete  skeleton  of  the  mammoth  was 


*  Osborn,  H.  F.,  "  Faunal  Eelations  of  Europe  and  America,"  p.  58. 
t  Howorth,  H.  H.,  "The  Mammoth  and  the  Drift." 
I  Tcherski,  J.  D.,  "  Das  Janaland,"  p.  474. 


MAMMOTHS   IN   ALASKA  87 

discovered  in  an  undoubtedly  pre-Glacial  deposit  at  Troizkoje, 
near  Moscow. 

In  Alaska  the  mammoth  is  the  only  elephant  that  has  been 
found  fossil.  In  the  United  States  its  remains  are  associated 
with  those  of  two  other  elephants,  viz.,  Elephas  columbi  and 
Elephas  imperator,  which,  according  to  Professor  Osborn,* 
are  analogous  to  the  European  Elephas  antiquus,  and  E. 
meridionalis.  The  ranges  of  these  species  overlap,  yet  their 
distribution  seems  to  imply  that  the  mammoth  was  the  last- 
comer,  or  that  it  became  modified  in  structure  further  south, 
giving  rise  to  the  two  other  species  of  elephants.  The  de- 
posits in  which  the  mammoth  occurs  in  the  United  States 
are  generally  looked  upon  as  Pleistocene.  But  in  the  Potter 
Creek  Cave  in  California  it  is  associated  with  Mastodon, 
Megalonyx  and  other  types  belonging  to  extinct  genera,  f 
This  cave  contains  nearly  fifty  per  cent,  of  extinct  species, 
and  if  situated  in  Europe  would  probably  be  classed  among 
Pliocene  deposits. 

Similar  cases  illustrating  the  invasion  of  Asiatic  types  by 
way  of  Alaska,  and  their  apparent  modification  in  character 
as  they  travelled  southward,  occur  in  almost  all  groups  of 
animals.  Sometimes,  however,  we  meet  with  instances  that  are 
very  difficult  to  explain  by  the  assumption  of  their  ancestors 
having  utilised  the  land  bridge  alluded  to.  The  magpie  (Pica 
rustica),  for  example,  is  a  handsome  and  strikingly  coloured 
bird  inhabiting  the  whole  of  Europe,  North  Africa,  central 
and  eastern  Asia  and  western  North  America.  Various  races 
and  varieties  are  recognisable  among  the  Asiatic  magpies, 
while  the  north.  African  form  is  likewise  distinct.  Curiously 
enough,  the  American  variety  resembles  the  European  form 
more  closely  than  it  does  any  of  the  Asiatic  ones,  and  it  occurs 
from  Alaska  to  Mexico,  and  eastward  as  far  as  the  Missouri 
Eiver,  whereas  no  magpies  at  all  have  been  noticed  in  the 
extreme  north-east  corner  of  Asia.  The  distribution  is  there- 
fore somewhat  discontinuous,  the  most  easterly  district  in 
Asia  where  it  is  known  being  southern  Kamchatka.  In  the 
extreme  south-west  of  its  American  range  in  southern 

*  Osborn,  H.  F.,  "Mammalian  Palaeontology,"  p.  111. 
t   Brown,  Barnuni,  "  Conard  Fissure,"  pp.  167 — 168. 


88  ORIGIN   OF  LIFE  IN  AMERICA 

California  quite  a  peculiar  yellow-billed  magpie  has  arisen, 
which  is  sometimes  distinguished  by  the  name  of  Pica  nutalli. 

It  is  not  at  all  evident  that  the  ancestors  of  these  American 
magpies  entered  America  by  way  of  Alaska,  and  yet  if  mag- 
pies had  originated  in  America  there  would  probably  be  many 
species  there ;  at  any  rate,  they  would  inhabit  the  whole  of  the 
continent,  and  perhaps  central  America  as  well.  Being  con- 
fined to  the  west,  and  differing  but  slightly  from  Old-WorJd 
farms,  their  origin  points  to  Asia.  At  the  same  time  the  fact 
that  the  American  magpie  is  more  like  the  European  form 
than  the  Asiatic  one  is  a  feature  which  cannot  be  lost  sight 
of.  Dr.  Diederich  discusses  the  problem  whether  the 
American  magpies  arrived  in  America  before  or  after  the 
Glacial  Epoch.  In  spite  of  the  fact  that  magpies  in  America 
are  entirely  migratory  and  have  lived  on  the  continent  suffi- 
ciently long  to  develop  the  peculiar  Calif  ornian  race  just 
referred  to,  Dr.  Diederich  *  inclines  to  the  belief  that  they 
entered  the  New  World  in  post-Glacial  times.  Without  any 
fossil  or  other  evidence  to  guide  us,  it  is  difficult  to  express 
an  opinion  on  this  subject.  But  it  seems  to  me  that  the 
magpie  should  be  placed  into  one  group  with  a  good  many 
other  forms  of  animal  life  which  reached  North  America  long 
before  that  event,  as  I  shall  more  fully  describe  in  one  of 
the  subsequent  chapters. 

Dr.  Gill,  as  I  mentioned  above  (p.  83),  expressed  the 
opinion  that  the  occurrence  of  Scaphirhynchus  in  Asia  pointed 
in  favour  of  an  older  land  connection  between  that  continent 
and  North  America.  The  fish  known  in  America  as  ;the 
shovel-nosed  sturgeon  (Scaphirhynchus  platyrhynchus)  is 
abundant  in  the  river  system  of  the  Mississippi  to  which  it 
is  confined.  It  is  now  known  that  its  nearest  relatives  are 
two  species  inhabiting  central  Asia  which  arena  longer  classed 
with  Scaphirhynchus,  but  are  placed  into  the  distinct  genus 
Kessleria.  All  these  ganoid  fishes  belong  to  a  very  ancient 
group,  most  of  which  are  extinct.  The  skeleton  of  the 
ganoids  is  generally  cartilaginous,  and  they  retain  many 
other  archaic  characters  in  their  anatomical  structure. 
Another  example  is  the  paddle -fish  (Polyodon  spathula).  It 

*  Diederich,  F.,  "  Verbreitung  der  Elstern,"  p.  51. 


THE  FISHES  OP  ALASKA  89 

likewise  lives  in  the  Mississippi  and  its  tributaries,  while  its 
next  of  kin3  Psephurus  gladius,  occurs  in  the  Yangtse  Kiang 
and  Hoang  Ho  rivers  in  China.  These  also  are  ganoid  fishes 
and,  like  the  true  sturgeon  and  bony  pike,  are  the  only  few 
remaining  members  of  a  very  ancient  and  formerly  abundant 
group  of  fresh- water  fishes.  The  fact  of  their  survival  in 
these  two  continental  centres  might  tempt  us  to  adduce  these 
instances  in  support  of  the  theory  stated  above,  that  Asia 
and  North  America  were  recently  connected  with  one  another 
by  land,  whereas  the  migration  of  these  fishes  is  an  old  story 
dating  back  to  some  remote  geological  period  when,  their  ances- 
tors no  doubt  spread  from  one  continent  to  the  other  by  means 
of  a  land  connection  which  probably  lay  further  south.  Their 
geographical  distribution  has  obviously  nothing  to  do  with 
the  subject  under  discussion,  which  concerns  a  geologically 
recent  event.  The  cat-fishes  or  horned-pouts  (Ameiurus) 
are  possibly  of  a  more  recent  origin.  They  swarm  in  every 
quiet  stream  and  pond,  especially  in  the  eastern  States  pf 
America.  A  single  species  (Ameiurus  cantonensis)  is  found 
outside  the  American  continent,  viz.,  in  China.  Finally 
I  may  mention  that  the  "  suckers  "  (Catostomus),  which  are 
very  numerous  in  the  American  streams,  are  confined  to 
North  America,  with  the  exception  of  one  species  (Catos,- 
tomus  rostratus),  which  inhabits  eastern  Siberia.  The  last 
case  certainly  indicates  a  former  land  connection  between 
North  America  and  Asia,  and  consequently  a  dispersal  from 
the  former  to  the  latter,  at  a  geologically  recent  date.  Still 
in  the  present  state  of  our  knowledge  we  are  unable  to  deter- 
mine whether  the  passing  across  to  Asia  of  these  fishes  coin 
cided  with  that  of  the  great  mammals  whose  dispersals  I 
have  endeavoured  to  elucidate. 

It  is  impossible  to  discuss  the  relationship  of  all  the  Asiatic 
to  the  Alaskan  groups  of  animals,  but  no  matter  what  class  or 
order  we  examine  with  a  view  to  testing  this  kinship,  we 
find  among  almost  all  of  them  some  indications  of  it.  Dr. 
Horvath,*  for  instance,  recently  dwelt  on  the  large  number  of 
species  of  Hemiptera  (a  group  including  bugs  and  allied 
insects)  common  to  Europe  and  North  America.  He  quoted  no 

*  Horvath,  G.,   "  Faunes  hernipterologiques,"  p.  7. 


90  OBIGIN  OF  LIFE  IN  AMERICA 

less  than  a  hundred  and  twenty-two  species  found  in  temperate 
and  northern  Europe,  and  also  in  North  America,  reasoning 
that  since  the  greater  number  of  them  also  live  in  northern 
Asia  they  must  have  spread  from  one  continent  to  another 
across  Bering  Strait.  He  does  not  definitely  state  that  he 
considers  the  Strait  to  have  been  a  land  surface  at  the  time 
these  species  are  supposed  to  have  passed  across  it.  Still  he 
emphasises  the  intimate  relationship  of  the  Alaskan  and  the 
opposite  Siberian  shore  fauna,  by  citing  the  names  of  four 
species  of  Hemiptera  which  are  confined  to  these  two 
countries. 

A  rather  striking  example  clearly  illustrating  the  gradual 
advance  of  a  genus  across  Asia,  and  its  final  immigration 
into  North  America,  is  shown  by  Parnassius,  a  genus  'of 
butterflies  to  which  the  European  "  Apollo  "  belongs.  The 
Apollo  group  of  butterflies  originated,  according  to  Mr. 
Austaut,  towards  the  latter  part  of  the  Tertiary  Era  in  Asia, 
at  the  time  when  some  of  the  great  mountain  chains  of  that 
continent  were  being  formed.  I  alluded  to  the  European 
species  of  Apollo  in  my  work  on  European  Animals,  gave  a 
map  of  their  distribution  and  enlarged  upon  their  origin.  I  am 
in  full  agreement  with  Mr.  Austaut's  views  as  to  the  Asiatic 
centre  of  dispersal.  The  only  point  in  which  I  differ  is  with 
regard  to  the  period  of  its  origin,  which  I.  believe  to  have 
been  considerably  earlier  than  Mr.  Austaut*  thinks  likely. 

In  Europe  we  possess  only  three  species  of  Parnassius, 
whereas  there  are  thirty-five  in  Asia,  Turkestan  being  the 
richest  country  in  Apollos.  Some  species  are  peculiar  to  the 
Altai  Mountains  in  Siberia,  and  as  we  go  eastward  new  forms 
replace  those  with  which  we  had  become  familiar.  In  Amur- 
land  there  are  others,  and  yet  when  we  cross  Bering  Strait  to 
Alaska  we  still  meet  with  an  Apollo  (P.  nomion)  which  also 
occurs  in  the  Altai  Mountains,  while  the  Calif ornian  Apollo 
(P.  clodius)  is  very  closely  related  to  Parnassius  clarius  of 
these  same  mountains.  The  Asiatic  character  has  thus  been 
retained  by  two  of  the  American  species.  Two  others,  Par- 
nassius thor  of  Alaska  and  Parnassius  sminthus,  are  quite 
distinct  from  any  others,  indicating  that  the  passage  from 

*  Austaut,  J.  L.,  "  Les  Parnassiens,"  pp.  62 — 63. 


AMEEICAN  APOLLOS  91 

Asia  to  America  of  the  genus  is  not  a  recent  event.  It 
must  have  taken  place  at  a  time  sufficiently  remote  from 
the  present  to  permit  the  gradual  evolution  of  the  two  new 
species  from  the  ancestral  forms.  This  may  possibly  have 
coincided  with  the  eastward  advance  of  the  mammals  referred 
to.  A  land  connection  in  the  neighbourhood  of  Bering  Strait 
would  certainly  have  facilitated  the  dispersal  of  these  butter- 
flies and  other  insects  just  as  much  as  that  of  mammals. 

In  a  discussion  on  the  relationship  of  the  Asiatic  and  North 
American  forms  of  another  genus  of  butterfly  (Vanessa),  Dr. 
Standfuss  *  also  supported  the  theory  of  the  former  land  con- 
nection between  Asia  and  North  America  in  pre-Glacial  times. 
The  Glacial  Epoch,  he  contends,  subsequently  segregated 
the  butterfly  fauna  into  insular  districts  in  which  many 
species  survived,  and  whence  they  afterwards  spread  to  other 
parts. 

Before  we  consider  the  land  bridge  problem  from  the  point 
of  view  of  the  marine  fauna,  some  remarks  on  the  general 
character  of  the  present  mammalian  fauna  of  Alaska  will 
be  of  interest.  Both  Labrador  and  Newfoundland,  the  two 
districts  in  the  east  which  seem  to  have  been  little  affected  by 
the  Glacial  drift,  and  on  which  the  still  existing  mammalian 
fauna  probably  survived  from  pre-Glacial  times,  were  found 
to  contain  a  certain  number  of  peculiar  species.  We  should, 
therefore,  expect  such  a  vast  region  as  Alaska,  which  was 
also  scarcely  affected  by  Glacial  drift  deposits,  to  contain 
even  a  larger  number  of  indigenous  species  of  mammals  that 
survived  the  Ice  Age  in  the  country.  We  do  not  positively 
know  that  any  mammals  survived  the  Ice  Age  in  Alaska,  but 
since  we  are  unacquainted  with  any  reasons  why  they  should 
not  have  done  so,  that  assumption  is  warrantable.  The  num- 
ber of  mammals  peculiar  to  the  country  is  surprisingly  large, 
and  this  alone  implies  that  these  animals  inhabited  the 
country  for  a  sufficiently  long  time  to  develop  characters 
distinguishing  them  specifically  from  those  of  the  neigh- 
bouring parts  in  North  America.  The  objection  has  been 
raised  that  American  naturalists  hold  somewhat  narrower 
views  as  to  specific  distinctions  than  are "  current  among 

*  Standfuss,  M.,  "  Palaearktische  Gross-Schmetterlinge,"  pp.  296—298. 


92 


ORIGIN  OF  LIFE   IN  AMERICA 


European  zoologists,  and  that  many  of  their  so-called  species 
are  nothing  more  than  varieties  or  races.  In  many  cases  this 
criticism  is  not  justified,  but  even  if  we  regarded  the  forty- 
five  species  of  mammals  peculiar  to  Alaska  merely  as  varieties, 
the  fauna  still  retains  a  remarkably  distinctive  character  which 
can  only  have  arisen  through  long-continued  isolation.  I 
herewith  give  a  list  of  the  species  of  mammals  confined  to 
Alaska.  In  doing  so  it  must  be  understood  that  I  am  not  com- 
mitting myself  to  any  opinion  as  to  their  specific  distinct- 
ness. 


Aloes  gigas. 
Rangifer  montanus. 
Oreamnos  kennedyi. 
Sciuropterus  yukonensis. 
Citellus  osgoodi. 

„       nebulicola. 

„       beringensis. 

„       barrowensis. 

„       stonii. 
Microtus  operarius. 

,,        unalascensis. 

,,        kadiacensis. 

„        yakutatensis. 

,,        sitkensis. 

„         innuitus. 

,,        abbreviatus. 
Ochotona  collaris. 
Tamias  caniceps. 
Peromyscus  sitkensis. 
Teonoma  saxamans. 
Evotomys  dawsoni. 
orca. 


Evotomys  wrangeli. 
Lemrnus  minusculus. 

nigripes. 

Fiber  spatulatus. 
Lepus  othus. 

„       poadromus. 
Synaptomys  wrangeli. 

,,  dalli. 

Vulpes  kenaiensis. 
„       pribilofensis. 
,,       beringensis. 
Ursus  middendorffi. 
„      kidderi. 
„      dalli. 
,,      eulophus. 
,,      kenaiensis. 
„      emmonsi. 
Mustela  kenaiensis. 

,,       arcticus. 
Sorex  tundrensis. 
,,     glacialis. 
,,     pribilofensis. 


The  late  Professor  Asa  Gray  was  the  first  to  draw  attention 
to  the  relationship  of  the  flora  of  America  and  that  of  Asia. 
He  was  struck  particularly  with  the  remarkable  resemblance 
of  some  of  the  plants  found  in  the  eastern  United  States  to 
those  inhabiting  Japan.  This  particular  feature,  however, 
will  be  discussed  in  one  of  the  subsequent  chapters.  It  was 
not  till  much  more  recently  that  botanists  became  acquainted 
with  the  intimate  floristic  relationship  between  Alaska  and 


MAMMALS   PECULIAK  TO   ALASKA  93 

north-eastern  Asia.  Professor  Engler  *  cites  a  large  number 
of  arctic-alpine  plants,  most  of  which  are  met  with  in  these 
two  regions,  and  extend  southward  in  America  along  the 
Eocky  Mountain  chain.  He  argues  that  some  of  the  species 
were  probably  capable  of  spreading  from  the  one  continent 
to  the  other  under  the  existing  conditions  of  land  and  water. 
Of  others  he  does  not  consider  that  they  could  have  drifted 
across  the  ocean  by  occasional  means  of  transport,  and  he 
urges  that  only  a  former  land  connection  in  the  north  could 
satisfactorily  explain  their  presence  in  Asia  and  North 
America. 

Finally  a  few  observations  on  the  land  bridge  problem  from 
the  marine  faunal  aspect  may  elucidate  some  doubtful  points. 
Dr.  Dallf  divides  the  existing  marine  fauna  of  the  north- 
eastern Pacific  into  three  zones,  viz.,  the  Oregonian,  Aleutian 
and  Arctic.  The  Oregonian  extends  from  Monterey  to  the 
Shumagin  Islands.  The  Aleutian  passes  westward  from  the 
Shumagin  Islands,  includes  the  Aleutian  chain,  and  reaches 
northward  to  the  floating  ice  in  Bering  Sea,  bounded  by  a 
depth  of  five  hundred  fathoms.  The  arctic  zone  stretches 
indefinitely  southward  beyond  the  five-hundred-fathom  line, 
and  is  bounded  in  the  north  by  floating  ice,  or  water  of  thirity- 
two  degrees.  Some  arctic  species  have  crept  southward  to  the 
northern  islands  of  Japan  and  Cape  Newenham,  while  a  series 
of  isolated  arctic  colonies  occur  from  Cook's  Inlet  southward 
and  eastward. 

Dr.  Dall's  views  are  mostly  derived  from  a  study  of  the 
marine  mollusca,  and  it  is  interesting  to  note  that  in  the 
main  points  they  are  confirmed  by  Miss  Eathbun  J  after  an 
examination  of  the  northern  Pacific  Crustacea.  She  states 
that  arctic  species  often  continue  southward  through  Bering 
Strait,  along  the  west  coast  of  Bering  Sea,  to  Okhotsk  Sea  and 
the  Kurile  Islands.  Some  of  them  extend  eastward  to  Puget 
Sound  and  even  further  south.  Miss  Eathbun  noticed  that  in 
exceptional  cases,  for  instance  Philyra  pisum  and  Cancer 

*  Engler,  A.,  "  Entwicklungsgeschichte  der  nordl.  Florengebiete," 
pp.  22 — 43. 

t  Ball,  W.  H.,  "  Marine  Faunal  Eegion  of  North  Pacific,"  p.  206. 

J  Eathbun,  Mary  J.,  "  Decapod  Crustaceans  of  North-West  Coast," 
p.  6. 


94  OKIGIN   OF   LIFE   IN   AMEEICA 

amphiaetus,  Japanese  species  are  found  to  occur  in  approxi- 
mately the  same  latitude  on  the  American  coast,  without 
obvious  connection  by  way  of  Alaska. 

The  Black  Stream  of  Japan,  the  "  Kuroshiwo,"  comparable 
to  the  Gulf  Stream  of  the  Atlantic  Ocean,  keeps  outside  the 
island  chain  of  the  east  coast  of  Asia,  sldrts  the  Aleutian 
Islands,  and  then  makes  itself  felt  on  the  south  coast  of 
Alaska.  The  fish  fauna  of  the  northern  Sea  of  Japan  has 
nineteen  per  cent,  of  species  in  common  with  the  south  coast 
of  Alaska.  With  the  Bering  Sea  the  latter  has  about  twice 
as  many  fishes  in  common.  All  of  these  are  forms  frequent- 
ing cold  seas.* 

Dr.    Dallf  recently   expressed   the   opinion,    based   on    a 
study  of  Tertiary  marine  deposits,  that  the  conditions  indi- 
cated by  the  faunas  of  the  post -Eocene  Tertiary  on  the  Pacific 
coast  from  Oregon  northward  are  a  cool  temperate  climate 
in  the  early  and  middle  Miocene,  a  warming  up  towards  the 
end  of  the  Miocene,  culminating  in  a  decidedly  more  warm- 
water  fauna  in  the  Pliocene,  and  a  return  to  cold,  if  not  prac- 
tically arctic,  temperature  in  the  Pleistocene.   Further  south, 
on  the  Californian  feoast,  the  Tertiary  marine  faunas,  espe- 
cially those  of  San  Pedro,  have  been  very  carefully  studied 
by  Professor  R.  Arnold.     The  Pliocene  fauna,  he  remarks, 
though  not  quite  similar  to  the  fauna  at  present  living  off 
San  Pedro,  still  contains  many  species  which  now  only  occur 
north  of  that  locality.     Many  of  these  northern  species  are 
limited  in  range  to  the  boreal  waters  north  of  Puget  Sound. 
Hence  he  concludes  that  these  Pliocene  deposits  were  laid 
down  in  water  much  colder  than  that  now  found  off  San  Pedro. 
In  the  lower  beds  of  the  Pleistocene,  he  continues,  the  cold 
climatic  conditions  prevalent  during  the  later  Pliocene  were 
giving  place  to  a  warmer  climate,  which  had  its  effect  on 
the  boreal  species  of  San  Pedro.     Southern  species  gradually 
increase    in   number  -while  northern  ones  become  scarcer. 
Finally  the  upper  Pleistocene  beds  contain  14'2  per  cent, 
of  species  that  are  only  now  found  living  south  of  San  Pedro, 


*  Schmidt,  P.,  "  Verbreitung  der  Eische  im  Stillen  Ocean,"  p.  564. 
t  Dall,  W.  H.,  "Climatic  Conditions  at  Nome,"  p.  457. 


NOETH   PACIFIC   MAEINE   FAUNA  95 

while  6*1  per  cent,  at  present  occur  exclusively  north  of 
this  locality.  Professor  Arnold*  is  thus  led  to  the  con- 
clusion that  semi-tropical  conditions  prevailed  during  the 
deposition  of  the  Pleistocene  formation.  He  also  emphasises 
the  fact  that  the  later  Tertiary  and  Pleistocene  faunas  of 
Japan  and  the  west  coast  of  the  United  States  resembled  one 
another  much  more  than  the  faunas  of  the  two  sides  of  the 
Pacific  do  at  the  present  time. 

Nothing  could  be  more  contradictory  than  the  two  state- 
ments of  Dr.  Dall  and  Professor  Arnold  as  to  the  climatic 
conditions  prevailing  in  two  portions  of  the  Pacific  coast  of 
North  America  in  Pliocene  and  Pleistocene  times.  It  seems 
almost  as  if  the  deposits  from  which  Dr.  Dall  derived  his  con- 
clusions were  not  contemporaneous  with  those  that  led  Pro- 
fessor Arnold  to  pronounce  the  views  just  stated.  It  is 
scarcely  possible  to  conceive  that,  while  a  warm -water  fauna 
existed  on  the  Oregon  and  Alaskan  coasts  in  Pliocene  times, 
California  should  have  had  a  cold  climate.  Arctic  conditions 
are  then  supposed  to  have  supervened  on  the  north  Pacific 
coast.  On  the  Californian  coast,  on  the  other  hand,  the  cold 
Pliocene  climate  is  stated  to  have  been  succeeded  by  a  semi- 
tropical  one  during  the  Pleistocene  Period. 

It  is  now  generally  recognised,  I  think,  that  Central 
America,  in  its  present  configuration,  originated  by  a  final 
union  of  pre-existing  independent  land-masses  in  Pliocene 
times.  That  an  inter-oceanic  current,  now  no  longer  exist- 
ing, might  have  produced  altogether  peculiar  climatic  con- 
ditions on  the  Californian  coast  in  Miocene  times  but 
not  later  seems  admissible.  If  we  suppose  that  the  Japanese 
"Kuroshiwo"  current  formerly  sent  part  of  its  warm 
waters  through  a  wider  opening  at  Bering  Strait  into  the 
Arctic  Ocean,  would  it  have  had  the  effect  of  inducing 
the  Mexican  fauna  to  advance  northward  and  the  arctic 
fauna  to  pour  southward  towards  the  coast  of  Oregon  ? 
I  doubt,  even  under  such  geographical  conditions,  whether 
the  Pleistocene  faunas  of  California  and  Oregon  could 
have  differed  to  such  an  extent  as  described  by  Dr.  Dall  and 

*  Arnold,  Balph,  "  Marine  Pliocene  and  Pleistocene  of  San  Pedro," 
pp.  65—67. 


96  OKIGIN   OF   LIFE   IN   AMERICA 

Professor  Arnold.  At  any  rate,  it  is  reasonable  to  infer  that 
a  rise  to  a  higher  temperature  of  the  northern  Pacific  Ocean, 
coupled  with  an  increased  conveyance  of  Asiatic  species  to 
the  American  coasts  and  a  northward  advance  of  southern 
forms  must  have  coincided  with  the  closing  of  Bering  Strait. 
And  it  was  not  until  Pliocene  times,  according  to  Professor 
jJ.;P.  Smith,*  that  the  marine  faunas  of  Japan  and  the  western 
coast  of  America  began  to  be  remarkably  similar,  many  species 
being  identical.  From  this  fact  we  must  conclude  that  inter- 
migration  between'the  two  continents  had  set  along  a  northern 
shore  line.  During  the  preceding  Miocene  Period  the  .marine 
fauna  of  California  consisted  of  endemic  species  mixed  with' 
southern  and  circumboreal  ones,  but  without  any  Asiatic 
admixture.  Consequently  there  was  probably  a  wide  com- 
munication between  the  Pacific  and  the  Arctic  Ocean,  favour- 
ing the  entrance  into  the  latter  of  a  warm  current  which 
profoundly  affected  the  Arctic  Regions.  The  curious  relation- 
ship to  Pacific  mollusks  which  is  noticeable  among  some 
forms  of  the  English  Crag  deposits  may  possibly  date  from 
this  theoretical  Miocene  current,  which  may  have  carried 
marine  species  right  across  the  Polar  Seas  to  Europe. 

At  the  beginning  of  the  Pleistocene  Period,  the  same  con- 
ditions existed,  according  to  Professor  Smith,  as  in  the  Upper 
Pliocene.  As  the  waters  of  the  Calif ornian  coast  gradually 
became  warmer,  he  remarks,  Mexican  species  began  to  .creep 
northward.  But  this,  he  says,  does  not  mean  that  connection 
with  Japan  was  cut  off.  The  continuation  of  the  conditions 
that  permitted  Japanese  species  to  migrate  to  California, 
merely  allowed  marine  animals  to  make  their  way  up  the 
American  coast  also.  Here  I  must  beg  to  differ  from  Pro- 
fessor Smith.  If  a  change  in  the  fauna  of  the  upper  Pleis- 
tocene of  California  took  place  as  asserted,  that  change  was 
in  all  probability  due  to  a  gradual  sinking  of  the  land  in 
the  north,  for  a  moderate  subsidence  in  northern  Alaska  at 
any  rate  has  been  recorded  by  Dr.  Dall  f  during  later  Pleisto- 
cene times.  A  gradual  modification  was  thus  brought  about 
in  the  disposition  of  land  and  water,  the  continents  of  Asia 
and  North  America  slowly  assuming  their  present  shapes. 

*  Smith,  J.  P.,  "  Periodic  Migrations,"  pp.  225—226. 
t  Ball,  W.  H.,  "  Neocene  of  North  America,"  p.  278. 


NOETHEEN   PACIFIC   IN   THE   PAST  97 

I  have  endeavoured  to  show  in  this  chapter  how  the  more 
striking  instances  of  relationship  among  the  animals  of  Asia 
and  North  America  can  be  explained,  how  they  arose  and 
under  what  climatic  conditions.    That  Alaska  was  once  joined 
by  land  to  the  opposite  shore  of  Asia  has  been  almost  uni- 
versally acknowledged  by  biologists  and  geologists.    But  for 
our  purpose  we  required  something  more  definite  than  a  state- 
ment such  as  that  of  Professor  Heilprin,*  "  it  appears  likely 
that  the  bears,  swine,  oxen,  sheep,  antelopes  and  elephants 
originated  in  the  Old  World,  whence  they  were  transplanted, 
by  way  of  some  land  connection  existing  in  the  north^  into 
the  New  World."     Even  Dr.  Arldt's  f  remark,  "the  bridge 
between  Asia  and  North  America  remained  until  the  Glacial 
Period/'  is  too  vague.    I  think  I  have  brought  together  suffi- 
cient data   to    show  that  a  land  connection  existed  in  the 
region  of  Bering  Strait  during  Pliocene  times  until  the  com- 
mencement, or  perhaps  until  the  end,  of  the  early  part  of  the 
Pleistocene  Period.  As  far  as  I  know,  the  only  fact  that  can  be 
brought  forward  against  such  an  assumption  is  the  discovery 
by  Dr.  Dall  J  of  marine  gravels  at  Nome,  in  Alaska,  contain- 
ing shells  which  he  believed  to  be  of  Pliocene  Age.  Consider- 
ing, on  the  other  hand,  that  the  gravels  in  question  only  con- 
tained one  distinct  species,  it  is  quite  possible  that  they  may 
not  be  so  old  as  Dr.  Dall  thinks.   And  even  if  their  Pliocene 
age  should  be  established  by  further  researches,  it  only  proves 
that  the  land  connection  was  not  so  wide  as  .we  are  apt  ,tq 
believe.    These  gravels  do  not  disprove  the  existence  of  the 
land  bridge,  for  Nome  is  situated  to  the  south  of  Bering  Strait 
on  the  shores  of  the  Bering  Sea. 

I  have  adduced  testimony  showing  that  Alaska,  not  only  in 
Pliocene  times,  but  also  during  part  of  the  Pleistocene  Period,, 
had  a  comparatively  mild  climate.  Many  of  the  larger 
mammals  seem  to  have  become  exterminated  within  more 
recent  times  owing  to  a  change  of  climate.  There  is  no  indi- 
cation of  any  wholesale  destruction  of  the  fauna  during  th-> 
Glacial  Epoch  followed  by  a  recent  introduction  from  the 

*  Heilprin,  A.,  "  Geographical  Distribution  of  Animals,"  p.  179. 
t  Arldt,  Th.,  "  Entwicklung  der  Kontinente,"  p.  293. 
t  Dall,  W.  H.,  "  Climatic  Conditions  at  Nome,"  p  457. 
L.A.  H 


98  OKIGIN   OF   LIFE   IN   AMERICA 

south.  If  such  an  event  had  happened  we  should  not  have  had 
such  a  large  percentage  of  peculiar  forms  of  animal  life  in 
Alaska,  and  more  southern  forms  ought  to  have  found  their 
way  there,  such  as  the  American  deer  and  many  Cithers./* 

It  would  seem,  therefore,  as  if  both  the  Atlantic  and  the 
Pacific  Ocean  became  closed  in  the  north  simultaneously  and 
remained  so  for  a  considerable  time  (Fig.  7).  The  southern 
shores  of  both  the  (great  land  bridges  were  then  under  the  direct 
influence  of  warm  ocean  currents  resulting  in  favourable  con- 
ditions for  the  growth  of  vegetation  and  the  food  supply 
for  large  mammals.  The  northern  shores  of  the  land 
bridges,  on  the  other  hand,  were  in  immediate  contact 
with  a  closed  Arctic  Ocean,  whose  waters  would  naturally 
have  remained  frozen  for  the  greater  part  of  the  year. 
During  winter  the  snowfall  all  round  the  northern  Atlantic 
and  northern  Pacific  Oceans  was  probably  considerable. 
The  land  being,  moreover,  at  a  higher  level,  this  would 
have  resulted  in  the  production  of  local  glaciers.  Marine 
transgressions  from  the  Arctic  Ocean  then  seem  to  have 
taken  place  across  northern  Russia,  as  I  described  in  my 
work  on  the  History  of  the  European  Fauna,*  and  across 
the  lowlands  of  arctic  Canada  as  indicated  on  pp.  46 — 49. 
My  views  on  the  Glacial  Epoch  and  its  nature  are  thus  at 
variance  with  those  held  by  most  geologists  of  the  present 
time.  They  agree  with  those  put  forward  by  Sir  William 
Dawson,f  and  are  more  in  accordance  with  the  current 
opinions  at  the  time  when  the  Glacial  Epoch  was  spoken  of 
as  the  "  Diluvial  Age." 

It  is  very  generally  believed,  as  I  mentioned  before,  that  the 
climate  in  northern  Europe  and  northern  North  America  was 
very  cold,  and  that  all  that  vast  region  which  is  covered  by 
the  deposit  known  as  "  Glacial  drift  "  had  been  invaded  during 
the  Glacial  Epoch  by  thick  masses  of  land  ice,  so  as  to  destroy 
practically  all  life  or  drive  it  far  southward  of  the  southern 
limits  of  the  drift.  I  stated  in  another  chapter  (p.  77)  that  I 
did  not  intend  to  make  a  special  point  in  discussing  the  origin 
of  the  Glacial  Epoch.  I  only  incidentally  bring  forward  a 

*  Scharff,  E.  F.,  ''History  of  European  Fauna,"  p.  172—184. 
t  Dawson,  W.,  "  Ice  Age  in  Canada." 


V          \ 


FlG.  7.- — Map  of  Northern  portion  of  Northern  Hemisphere,  with  supposed  land 
connections  in  early  part  of  Glacial  Epoch  (shaded)  and  extent  of  sea  (white). 


[To  face  p.  98. 


BERING   STKAIT  LAND   BRIDGE  99 

theory  of  its  origin  and  nature  which  appear  to  me  to  agree 
better  with  the  geological  history  of  the  boreal  fauna  and  flora, 
as  far  as  we  are  able  to  ascertain  them,  than  the  hypotheses 
which  have  been  so  widely  accepted  by  scientific  men. 

Professor  Shaler  *  reminds  us  that  the  extension  of  rela- 
tively warm  climates  which  has  occurred  at  certain  stages 
of  the  Earth's  history  is  perhaps  explicable  in  an  equally 
simple  manner  as  that  of  the  Glacial  Epoch.  He  expresses 
the  belief  that  if  Bering  Strait  were  as  rea'dily  open  to  the 
warm  stream  of  the  Pacific  or  "  Kuroshiwo  "  as  the  Atlantic 
is  open  to  the  Gulf  Stream,  the  temperature  of  the  region  a*bout 
the  North  Pole  would  be  lifted  by  at  least  thirty  degrees  above 
its  present  mean  annual.  Indeed,  if  the  Glacial  Epoch  had 
been  due  to  a  simultaneous  closing  of  the  Arctic  Ocean  to  the 
genial  influences  of  both  Atlantic  and  Pacific,  a  mild  climate 
all  over  the  Arctic  Regions  must  have  coincided  with  a  more 
copious  flow  of  the  "  Kuroshiwo  "  into  the  Arctic  Ocean.  And 
here  apparently  lies  the  great  stumbling  block  to  my  theory 
on  the  origin  of  the  Glacial  Epoch.  If  the  warmer  tempera- 
ture in  the  Arctic  Regions  in  Miocene  and  Oligocene  times 
had  been  due  to  a  wider  Bering  Strait,  and,  consequently,  to 
the  fact  that  a  greater  volume  of  the  "  Kuroshiwo  "  then 
poured  into  the  Arctic  Ocean,  how  are  we  to  account  for  the 
faunistic  affinities  existing  between  Asia  and  North  America 
during  this  part  of  the  Tertiary  Era  ?  There  are  numbers  of 
animals  in  North  America  which  have  an  Asiatic  ancestry,  hut 
could  not  have  entered  the  Continent  with  the  great  invasion 
that  I  described  as  crossing  the  Bering  Strait  land  bridge. 
(These  and  many  other  facts  point  to  the  existence  of  a  land 
bridge  between  Asia  and  North  America  in  early  Tertiary 
times.  All  the  same,  several  important  features  imply  that 
before  the  Pliocene  Period  the  "  Kuroshiwo  "  really  sent  its 
warm  waters  altogether  to  the  Arctic  Ocean. 

As  I  mentioned  above,  no  Japanese  affinities  are  recognis- 
able in  the  American  Miocene  marine  fauna.  On  the  other 
hand,  there  is  some  evidence  that  the  Miocene  floras  of 
Sakhalin  and  Japan  were  intimately  related  to  the  Miocene 
flora  of  North  America.  These  apparently  contradictory 

*  Shaler,  N.  S.,  "  Nature  and  Man  in  America,"  p.  143. 

H2 


TOO  ORIGIN   OF   LIFE   IN   AMEKICA 

evidences  can  only  be  due  to  the  fact  that  a  portion  of  the 
Pacific  coast  of  North  America  was  connected  by  land  in  Mio- 
cene times  with  Sakhalin  and  Japan,  whereas  the  "  Kuro- 
shiwo  "  flowed  northward  between  these  islands  and  the  main- 
land of  Asia.  In  the  subsequent  chapters  the  evidence  which 
has  led  me  to  these  conclusions  will  be  more  fully  dealt  with. 


CHAPTER    V 

THE    ROCKY    MOUNTAINS 

FROM  Alaska  we  retrace  our  steps  to  Canada,  'by  that  magni- 
ficient  mountain  range  popularly  known  as  the  "  Rockies." 
I  have  already  mentioned  that  the  Rocky  Mountains  prac- 
tically end  near  the  shores  of  the  Arctic  Ocean.  They  begin 
in  northern  Mexico.  Although  we  can  approximately  fix 
the  beginning  and  end  of  this  vast  range  of  mountains  and 
even  its  eastern  border,  the  western  boundaries  are  more 
vague  and  indefinite.  In  British  Columbia,  which  is  so  famed 
for  its  grand  and  impressive  scenery,  its  rugged  mountains 
and  great  forests,  the  northern  spurs  of  the  Cascade  Moun- 
tains appear  to  merge  into  the  Rockies,  so  that  it  becomes  a 
matter  of  some  difficulty  to  discriminate  clearly  between  the 
two.  Further  south  the  Rocky  Mountains  cross  the  high 
plateau  of  Wyoming,  sometimes  spoken  of  as  the  "  Laramie 
region."  We  also  meet  here  the  complex  mountain  groups  to 
which  the  name  of  "  Stony  Mountains  "  has  been  applied. 
South  of  the  plateau  the  mountains  again  grow  more  irregular 
and  lofty  than  to  the  north  of  it.  Another  great  plateau  covers 
part  of  southern  Utah,  western  Colorado',  New  Mexico  land 
northern  Arizona.  With  a  height  of  over  6,000  feet  above 
sea-level,  this  region  has  suffered  great  erosion,  and  is  deeply, 
trenched  by  fantastic  gorges  which  intersect  it  in  every  direc- 
tion. The  most  famous  of  them,  the  Colorado  Canon,  is  a 
clean-cut  chasm,  which,  in  the  course  of  ages,  has  been  slowly 
carved  by  the  river  to  the  stupendous  depth  of  6,000  feet 
in  the  horizontal  strata. 

It  is  not  only  the  lover  of  scenery,  but  particularly  the 
naturalist  and  palaeontologist  who  appreciate  the  unrivalled 
attractions  of  the  Rocky  Mountains.  These  mountains,  more 
over,  have  been  the  direct  means  of  exposing  what  are  probably 


102  OKIGIN  OF  LIFE  IN  AMERICA 

the    most    valuable    and    extensive    deposits    of    fossils    in 
existence.* 

As  we  enter  the  United  States,  proceeding  along  the  Rocky 
Mountains,  we  soon  find  ourselves  in  the  midst  of  the  Miocene 
and  the  lower  Oligocene  beds  (White  River)  of  Montana. 
Further  south,  in  Wyoming,  we  come  to  the  Wind  River  beds, 
while  on  our  left  to  the  feast  lie  the  Wasatch  deposits,  both 
of  which  belong  to  the  lower  Eocene.  Westward  we  cross 
into  the  middle  Eocene  Bridger  and  Washakie  beds  of 
Wyoming,  and  also  the  upper  Eocene  Uinta  of  Utah.  Much 
further  south  we  finally  meet  with  the  famous  Puerco,  Tor- 
rejon  and  Wasatch  formations  of  the  San  Juan  basin  in  New 
Mexico,  which  are  held  to  be  of  basal  and  lower  Eocene  age. 
Owing  to  the  labours  chiefly  of  Leidy,  Marsh,  Cope,  Scott, 
Osborn,  Wortman,  Matthew,  Hatcher,  and  others,  a  most  re- 
markable assemblage  of  fossils  has  been  obtained  among  these 
immensely  rich  deposits.  Our  knowledge  of  the  former 
inhabitants  of  North  America  has  thus  greatly  increased 
within  recent  years,  and  has  aided  us  in  tracing  the  gradual 
changes  of  land  and  water  that  the  continent  has  undergone 
in  past  times.  Great  efforts  are  now  being  made  to  work  out 
the  correlation  of  the  North  American  mammal -bear  ing 
horizons.  I  propose  to  return  to  this  subject  later  on,  and 
need  not  dwell  on  it  any  longer  at  present. 

Although  glaciers  have  now  almost  entirely  disappeared 
from  the  Rocky  Mountains,  abundant  proofs  have  been  left 
of  their  past  presence  in  the  shape  of  moraines,  and  polished 
as  well  as  striated  surfaces.  These  signs  of  former  glaciation 
are  very  different  from  the  thick  mantle  of  drift  that  we 
noticed  in  Canada,  and  which  is  likewise  attributed  to  the 
action  of  glaciers.  Only  the  highest  summits  and  the  most 
elevated  valleys  of  the  Rocky  Mountains  were  ever  occupied 
by  ice,  and  there  does  not  appear  to  be  any  sign  of  a  'deposit 
in  the  whole  range  resembling  the  northern  drift.f 

These  glaciers,  no  doubt,  owed  their  existence  to  a  greatly 
increased  precipitation  of  moisture  in  the  Rocky  Mountains 
during  the  Ice  Age,  for  we  possess  quite  an  unmistakable 


*  Russell,  I.  C.,  "  North  America,"  pp.  122—136. 
t  Whitney,  J.  D.,  "  Climatic  Changes,"  pp.  64—72. 


GEEAT   SALT  LAKE   BASIN  103 

record  of  a  past  humid  period  in  the  basin  of  the  Great  Salt 
Lake  in  Utah.  All  round  the  present  lake  we  find  a  most 
interesting  series  of  terraces  at  varying  heights,  which  clearly 
represent  ancient  shore -lines.  It  has  thus  been  established 
that  in  Pleistocene  times,  during  its  greatest  development, 
the  lake  had  the  enormous  area  of  more  than  19,000  square 
miles,  that  is,  nearly  the  size  of  Lake  Michigan,  with  a  depth 
of  about  1,000  feet.  This  ancient  "  Lake  Bonneville,"  as  it 
has  been  called,  has  since  been  greatly  reduced  in  size  by  the 
slowly  increasing  aridity  of  the  country.  Its  diminutive 
descendant,  the  Great  Salt  Lake,  is  rapidly  drying  up,  ita 
average  depth  being  only  twenty  feet.  Other  large  fresh-water 
lakes  existed  in  the  Great  Basin  during  the  Glacial  Epoch. 

Sometimes  it  is  customary  to  include  the  western  Sierra 
Nevada  and  Cascade  Mountains  under  the  term  "  Rocky 
Mountains."  Asa  Gray  and  Sir  Joseph  Hooker  have  even 
added  to  this  area  that  of  the  Great  Basin  in  their  account 
of  the  Kocky  Mountain  flora.  More  recently  the  distinctive- 
ness  of  these  two  mountain  systems  is  being  more  generally 
recognised.  The  forests  of  the  Kocky  Mountains  are  dis- 
tinguished from  those  of  the  eastern  States  by  the  prevalence 
of  the  pyramidal  evergreen  conifers,  whereas  in  the  east  the 
trees  are  round-headed  and  mostly  deciduous.  The  endemic 
flora,  consisting  of  thirty-three  per  cent,  of  all  the  plants 
found  in  the  Rocky  Mountains,  forms  a  prominent  element.* 

We  have  noticed  that  some  of  the  alpine  plants  inhabiting 
the  White  Mountains  are  unknown  in  western  America,  for 
instance,  Diapensia  lapponica  and  Loiseleuria  procumbens. 
On  the  other  hand,  a  large  number  of  the  alpine  Kocky  Moun- 
tain species  do  not  occur  in  the  east,  whereas  a  few,  such  as 
Rhododendron  lapponicum,  Arctostaphylos  alpina,  Rubus 
chamaemorus  and  Veronica  alpina,  are  common  to  both,  point- 
ing to  the  great  antiquity  of  this  element  in  the  flora.f 
Many  of  the  plants  occur  also  in  Asia ;  others  are  closely 
related  to  arctic-alpine  species.  Most  of  the  endemic  element 
of  the  Rocky  Mountain  flora  has  clearly  been  derived  from  that 


*  Gray,  A.,  and  J.  D.  Hooker,    "Vegetation    des   Eocky  Mountain 
Gebietes,"  p.  267. 

t  Eydberg,  P.  A.,  "Composition  of  Rocky  Mountain  Flora,"  p.  870. 


104  OEIGIN   OF   LIFE   IN   AMEEICA 

of  the  lower  slopes  of  the  mountains,  and  to  it  belong  the 
typically  American  alpine  species.  They  reach  their  greatest 
development  in  the  southern  portion  of  the  Eockies. 

One  of  the  most  remarkable  features,  which  I  shall  have 
occasion  to  draw  attention  to  again  in  another  chapter,  is  the 
occurrence  in  the  Eocky  Mountains  of  some  species  of  plants, 
which  reappear  in  the  southern  Andes,  without  being  repre- 
sented either  in  the  Mexican  highlands  or  in  the  tropical 
Andes.  Among  these,  Professor  Engler  *  mentions  the 
dwarf  gentian  (Gentiana  prostrata),  the  mealy  primrose 
(Primula  farinosa),  the  hoary  draba  (Draba  incana)  and 
the  alpine  foxtail  (Alopecurus  alpinus).  All  these  are 
common  well-known  European  species.  A  few  more  have 
since  been  added  by  Professor  Bray  f  This  small  group 
of  species  is  of  peculiar  interest,  not  only  because  some- 
what analogous  instances  of  distribution  occur  among  insects, 
but  also  because  this  feature  is  by  no  means  limited  to 
mountain  forms.  In  another  chapter  I  shall  allude  to  :a 
number  of  species  inhabiting  the  arid  regions  of  south- 
western North  America  that  likewise  are  quite  unknown  in  the 
moist  tropical  and  sub -tropical  belts  of  country  to  the  south, 
yet  reappear  in  the  extreme  south  of  South  America.  Whether 
all  these  species  possess  particular  facilities  for  dispersal 
over  wide  areas  or  whether  former  conditions  of  land  and 
water  were  more  suitable  than  they  are  at  present  for  dis- 
persal will  be  discussed  later  on  (p.  414). 

The  fauna  of  the  Eocky  Mountains  resembles  the  flora  in 
its  composition,  except  that  among  the  higher  animals,  at  any 
rate,  the  species  are  almost  all  endemic.  Two  kinds  of  animals 
in  particular  are  associated  with  the  Rocky  Mountains  in 
sportsmen's  minds,  namely,  the  mountain  sheep,  or  big-horn, 
and  the  Eocky  Mountain  goat.  The  former  used  to.  be  known 
as  Ovis  canadensis.  But  from  the  systematic  mill  of  the 
zoologist,  as  Dr.  A.  E.  Brown  J  puts  it,  have  been  produced1 
seven  new  species  and  sub-species,  all  very  closely  re- 
lated to  one  another.  As  already  stated,  the  Kamchatkan 

*  Engler,  A.,  "Entwicklungsgeschichte,"  II.,  p.  256. 

t  Bray,  W.  L.,  "  Eolations  of  North  American  Flora,"  p.  713. 

J  Brown,  A.  E.,  "  Zoology  of  North  American  Big  Game,"  p.  69. 


AMEEICAN   MOUNTAIN    SHEEP  105 

sheep  (Ovis  nivicola)  is  more  nearly  akin  to  the  American 
sheep  than  it  is  to  other  Asiatic  ones,  and  the  occurrence 
on  both  sides  of  Bering  Strait  of  such  near  relations 
forms  one  of  the  strongest  buttresses  for  the  belief  in 
a  geologically  recent  land  connection  between  Asia  and 
North  America  in  the  neighbourhood  of  Bering  Sea.  The 
various  forms  of  American  sheep  are  entirely  confined  to  the 
western  mountain  region,  where  they  are  found  from  the 
Alaska  mountains  to  the  mountains  on  the  long  peninsula 
of  Lower  California,  and  eastward  as  far  as  Yellowstone  Park. 
The  home  of  the  big-horn  is  the  loftiest  rim-rock  of  the  high 
mountain  plateaux,  or  the  most  rugged  and  forbidding  bad- 
lands of  the  middle  altitudes.  In  summer,  says  Dr.  Horna- 
day,*  its  favourite  pastures  are  the  treeless  slopes  above  the 
timber-line,  and  in  winter  it  paws  through  the  snows  of  the 
mountain  meadows  to  reach  the  tallest  spears  of  grass.  When 
the  raging  storms  and  deep  snows  of  winter  drive  the  elk  and 
deer  down  into  the  villages  for  food  and  shelter,  the  mountain 
sheep  makes  no  perceptible  change  in  its  habitat.  Its  agility 
is  nothing  short  of  marvellous,  and,  from  its  wariness  and  diffi- 
culty of  approach,  it  is  a  favourite  object  of  pursuit  of  the 
experienced  hunter. 

If,  as  it  seems  likely,  the  American  mountain  sheep  has 
entered  North  America  from  north-eastern  Asia  within  recent 
geological  times,  the  fact  of  its  having  spread  to  Lower  Cali- 
fornia and  developed  several  distinct  forms  is  an  argument 
in  favour  of  a  pre- Glacial  immigration.  That  sheep  had 
already  penetrated  to  North'  America  in  Pliocene  times  is 
also  proved  by  the  discovery  of  the  horn  cores  of  a  sheep 
(Ovis  scaphoceras)  in  northern  Nicaragua. f 

The  comparatively  dull-witted  Kocky  Mountain  goat  (Ore- 
amnos  montanus)  shares  with  the  big-horn  the  almost  inac- 
cessible peaks  and  ridges  of  the  Rocky  Mountains,  but,  being 
clumsy  and  slow,  it  rarely  ventures  far  from  its  usual  haunts. 
Unlike  the  sheep,  the  Rocky  Mountain  goat  has  a  very  local 
and  discontinuous  range. £  It  seems  almost  as  if  its  original 
home  had  been  in  the  coast  ranges  of  Oregon  and  Washington, 

*  Hornaday,  W.  T.,  "  Notes  on  the  Mountain  Sheep,"  p.  77. 
t  Lucas,  F.  A.,  "  Fossil  Bison  of  North  America,"  p.  756. 
t  Grant,  Madison,  "The  Eocky  Mountain  Goat,"  p.  9. 


106  ORIGIN   OF   LIFE   IN   AMERICA 

and  that  it  had  then  spread  northward  to  British  Columbia 
and  southern  Alaska,  and  eastward  to  the  Rocky  Mountains. 
Its  whole  distribution  is  thus  confined  to  the  north-western 
United  States  and  western  Canada.  <The  term  "  goat  "  is  really 
a  misnomer.  It  is  not  a  true  goat,  nor  yet  a  true  antelope. 
We  might  with  more  justification  call  it  a  "  goat-antelope." 

In  some  respects  it  resembles  the  European  chamois 
(Rupicapra),  in  others  the  serow  and  goral  (Nemorrhaedus) 
and  the  takin  (Budorcas) .  The  last  three  are  confined  to  Asia, 
and  all  of  them,  though  generically  distinct  from  the  Rocky 
Mountain  goat,  belong  to  the  same  group  of  goat-antelopes. 

A  species  of  Nemorrhaedus  occurs  in  the  mountains  of 
Japan  and  northern  China,  and  we  might,  with  Dr.  Brown, 
be  tempted  to  assume  that  Oreamnos  has  arisen  in  America 
from  some  Pleistocene  immigrant  of  the  genus  Nemor- 
rhaedus.* But  surely  the  genus  Oreamnos,  to  which  the 
Rocky  Mountain  goat  belongs,  must  be  a  very  ancient  one. 
The  peculiar  discontinuous  range  of  the  whole  group  implies 
antiquity.  The  remains  of  the  mountain  goat  have  been  dis- 
covered in  Potter  Creek  Cave  of  California,  while  Mr.  Cragin 
is  said  to  have  described  a  fossil  species  of  Nemorrhaedus 
from  the  Pleistocene  of  Colorado.  I  have  not  been  able  to 
trace  the  description  or  further  particulars.  At  any  rate, 
the  more  remote  origin  of  Oreamnos  is  shrouded  in  obscurity. 
We  certainly  have  no  definite  evidence  that  its  ancestors  came 
from  Asia  in  Pleistocene  times.  They  probably  reached  the 
continent  much  earlier. 

The  Rocky  Mountain  goat  occasionally  falls  a  victim  to  the 
cougar  or  puma,  better  known  in  the  west  as  the  "  mountain 
lion,"  which,  like  its  prey,  is  a  typically  American  animal. 
From  a  distributional  point  of  view  it  is  one  of  the  most 
remarkable  mammals,  as  it  exceeds  all  others  in  the  great 
extent  of  its  range.  Its  utter  indifference  to  climatic  condi- 
tions is  shown  by  its  occurrence  from  southern  Patagonia 
right  through  the  tropics  to  western  Canada.  It  flourishes 
from  the  plains  of  Florida  to  the  regions  of  the  permanent 
snows  in  the  Rockies  and  Andes.  It  is  true  that  those  who 
take  note  of  small  differences  no  longer  believe  in  one  species 

*  Brown,  A.  E.,  "  North  American  Big  Game,"  p.  75. 


KOCKY  MOUNTAIN   GOAT  107 

possessing  this  vast  range.  Like  almost  all  other  mammals, 
the  cougar  (Felis  concolor),  which  in  all  its  essential  habits 
and  traits  remains  the  same,  whether  living  in  mountain, 
open  plain  or  forest,  under  arctic  cold  or  tropical  heat,  has 
yet  been  split  up  into  several  distinct  species. 

The  nearest  Old  World  relations  of  the  cougar  are  the  lion 
and  tiger,  both  of  which  differ  from  it  very  strikingly  in  size, 
habit  and  colour.  It  is  perfectly  obvious,  therefore,  that  it 
is  not  a  geologically  recent  immigrant  from  Asia.  Two  very 
closely  allied  species  of  large  cats,  moreover,  have  been  dis- 
covered in  Pleistocene  deposits  in  Argentina ;  while  the 
cougar  itself  has  left  its  remains,  along  with  those  of  extinct 
members  of  the  cat  tribe,  in  the  Conard  Fissure.  Another 
large  cat  (Felis  hillianus)  has  been  found  fossil  by  Professor 
Cope  in  the  Blanco  formation  of  Texas,  this  being  now  looked 
upon  as  middle  Pliocene.  Hence  it  is  probable  that  the 
ancestors  of  the  cougar  already  flourished  in  North  America 
as  well  as  in  the  southern  continent  in  Pliocene  times.  The 
facts  of  its  recent  distribution  seem  to  point  to  its  having 
entered  North  America  from  the  south,  and  it  may  pos- 
sibly have  done  so  in  Pliocene  times  when  the  northern 
continent  became  definitely  connected  with  South  America. 
Further  details  as  to  its  early  history  are  still  lacking. 

As  we  descend  the  mountains  through  the  forest  belt  and 
finally  reach  the  foot-hills,  we  meet  with  two  large  ungulates 
whose  acquaintance  we  have  not  hitherto  had  an  opportunity 
of  making.  Both  of  these  are  confined  to  the  western  States, 
and  are  well  known  to  the  hunters  of  the  Eocky  Mountain 
region.  The  black-tail,  or  mule  deer  (Odocoileus  hemionus), 
as  it  is  often  called  on  account  of  its  big  prominent  ears,: 
seems  at  first  sight  not  to  be  very  different  from  the  American 
elk  or  wapiti,  except  in  size.  But  the  latter  belongs  to  quite 
a  different  genus.  If  we  examine  the  antlers  of  the  two  more 
carefully,  we  notice  that  the  brow  tines  are  lacking  in  the 
mule  deer.  There  are  also  distinctions  in  the  skull,  while 
the  lower  parts  of  the  meta  carpal  bones  of  the  front  limbs 
are  retained  in  the  mule  deer.  The  wapiti  deer  is  descended 
from  an  Old  World  stock  which,  as  I  explained  (p.  68), 
crossed,  over  from  Asia  by  a  land  bridge  in  Pliocene  or  early 
Pleistocene  times.  In  it  only  the  upper  metacarpals  remain, 


108  OKIGIN    OF   LIFE   IN   AMEEICA 

and  it  differs  in  other  fundamental  characters  from  the  mule 
deer,  which  has  apparently  no  near  relations  in  the  Old  World, 
and  which  we  may  justly  call  the  true  American  deer. 

Fossil  remains  of  the  mule-deer  have  been  found  in  the 
Conard  Fissure.*  The  fossil  bones  of  other  deer  from  the 
Pleistocene  of  Illinois,  Iowa,  Wisconsin  and  Indiana,  have 
been  referred  to  extinct  species  of  the  genus  Odocoileus  to 
which  the  mule-deer  belongs.  No  Pliocene  or  older  traces 
of  this  genus  have  as  yet  been  discovered  in  North  America, 
if  we  adopt  the  generally  accepted  view  of  the  Conard  Fissure 
being  of  Pleistocene  age.  Altogether  there  are  three  fairly 
distinct  species  of  the  type  of  the  mule-deer  in  North  America, 
namely  the  one  I  have  just  described,  the  white-tailed  deer 
(Odocoileus  virginianus)  and  the  black-tailed  Columbian  deer 
(0.  columbianus) . 

It  is  of  considerable  interest  to  know  that  this  genus  lives 
not  only  in  Central  America,  but  right  to  the  southern  ex<- 
tremity  of  South  America  in  Chile.  This  fact  alone  is  remark- 
able,  for  nowhere  else  in  the  world  are  deer  found  south  of  the 
Equator.  They  are  entirely  absent  from  Africa  and  Australia. 
However,  it  is  by  no  means  the  only  noteworthy  circumstance 
about  this  American  group  of  deer.  Those  who  are  ac- 
quainted with  the  habits  and  life  history  of  the  deer  tribe 
know  that  the  young  of  deer  with  large  branching  antlers< 
at  first  possess  no  antlers.  Afterwards  small,  simple  and 
unbranched  processes  appear  on  their  heads.  From  year 
to  year  they  are  shed  and  new  ones  take  their  place,  and  these 
are  always  a  little  more  complex  than  the  previous  ones.  The 
gradual  development  of  the  race  seems  to  follow  that  of  the 
individual.  It  is  only  in  the  more  recent  geological  periods 
that  deer  with  branching  antlers  make  their  appearance.  As 
we  go  back  to  earlier  deposits  the  deer  skulls  only  bear  simple 
antlers  with  one  or  two  branches.  In  still  older  strata  we 
meet  with  deer  that  were  devoid  of  anflers,  while  they  gene- 
rally possessed  long  canine  teeth  which  no  doubt  were  useful 
as  organs  of  defence.  It  has  been  rightly  argued  that  the 
complex  antlers  have  only  been  developed  in  comparatively 
recent  geological  times,  and  that  deer  with  simple  antlers 

*  Brown,  Barnum,  "Conard  Fissure,"  p.  205. 


AMERICAN   MULE   DEER  109 

which  we  find  living  here  and  there  in  isolated  districts,  are 
more  ancient  in  point  of  origin. 

In  South  America  we  have  still  living  at  the  present 
moment  deer  of  the  type  of  the  mule-deer,  only  smaller, 
with  simple  forked  antlers.  Other  still  smaller  deer  possess 
merely  minute  spike-antlers.  Extinct  deer,  moreover,  with  all 
the  different  kinds  of  antlers,  have  been  observed  in  South 
American  Pleistocene  and  Pliocene  deposits.  One  species 
(Odocoileus  avius),  which,  according  to  Professor  Ameghino, 
belongs  to  the  group  with  complex  antlers,  has  even  been 
noticed  in  the  upper  Miocene  of  Argentina. 

Both  fossil  and  recent  evidence  thus  clearly  points  to  South 
America  as  the  source  of  these  true  American  deer.  If  we 
supposed  that  the  ancestors  of  the  North  American  species 
of  Odocoileus  had  penetrated  northward  in  Pliocene  times, 
when  Central  America  assumed  its  present  shape,  we  should 
have  a  reasonable  explanation  for  the  fact  that  the  genus 
has  never  spread  to  the  peninsula  of  Alaska,  nor  into  north- 
eastern Canada  and  Newfoundland. 

What  prevents  the  general  adoption  of  the  theory  of  the 
South  American  origin  of  this  group  of  deer  ?  Clearly  the 
fact  that  while  the  deer  family  (Cervidae)  is  represented" 
from  the  Oligocene  to  the  most  recent  deposits  in  Europe, 
it  only  makes  its  appearance  in  South  America  in  the  upper 
Miocene.  The  original  home  of  the  family  is  therefore 
believed  to  be  in  the  northern  hemisphere,  and  this  assump- 
tion is  strengthened  by  the  circumstance  that  nowhere  except 
in  South  America  have  deer  penetrated  to  the  southern  hemis- 
phere. Since  it  is  inadmissible  to  argue  that  mammals  so 
near  akin  as  the  Old  World  and  New  World  deer  should  have 
appeared  quite  independently  of  one  another  in  two  distinct 
centres,  these  affinities  can  only  be  explained  by  migration 
from  the  one  centre  to  the  other.  According  to  most  palaeonto- 
logists who  expressed  an  opinion  on  this  problem,  the  South 
American  ideer  could  only,  for  the  reasons  stated,  have  entered 
South  America  from  North  America.  Whether  they  were 
developed  in  the  Old  World  or  the  New,  it  is  evident,  remarks 
Mr.  Lydekker,*  that  the  American  deer  originated  in  the 

*  Lydekker,  B.,  "  Deer  of  all  Lands,"  p.  245. 


110  ORIGIN   OF   LIFE   IN   AMERICA 

northern  hemisphere,  and  that  they  are  comparatively  modern 
immigrants  into  South  America,  where  they  now  attain  their 
maximum  development. 

Mr.  Lydekker  gets  over  the  difficulty  of  the  simple-antlered 
South  American  deer,  or  brockets  as  they  are  called,  by  the 
admission  that  because  they  are  unknown  in  North  America, 
they  are  not  ancestral  forms.  He  thinks  they  should  be 
regarded  as  degraded  or  arrested  types  of  the  group  (p.  296). 

Professor  Marsh*  was  inclined  to  look  upon  the  North 
American  Leptomeryx  as  the  probable  progenitor  of  the 
Cervidae.  His  suggestion  led  to  further  researches  on  the 
part  of  Dr.  Matthewf  who  supplied  a  connecting  link  in  the 
chain  of  ancestry  of  Odo,coileus  in  the  Miocene  Blastomeryx. 
That  Dr.  Matthew's  view,  however,  is  not  generally  accepted 
may  be  gathered  from  Professor  Osborn's  f  recent  remark  in 
reference  to  the  Pleistocene  Period  in  North  America,  that 
among  the  newly  entering  northern  forms  are  Odocoileus, 
Ursus  and  Erethizon.  Professor  Osborn's  §  opinion  is  that 
the  origin  of  the  Cervidae  will  probably  prove  to  be  Asiatic. 
I  quite  concur  in  the  view  that  they  are  of  Old  World  origin, 
and  yet  I  hold  that  the  ancestors  of  the  North  American 
Odocoileus  have  invaded  the  northern  continent  from  South 
America.  The  remote  ancestors  of  Odocoileus  must,  there- 
fore, have  penetrated  from  the  Old  World  to  South  America 
without  attaining  North  America.  How  they  have  done  so  is 
the  problem  I  shall  endeavour  to  solve. 

Later  on,  when  we  come  to  deal  with  the  zoogeographical 
relationship  of  South  America  and  Africa,  I  shall  show  that 
we  possess  valuable  evidence  for  the  belief  in  a  former  land 
connection  across  the  southern  Atlantic  between  these  conti- 
nents. This,  however,  will  not  help  us  in  explaining  the  deer 
problem,  because  no  deer  have  ever  been  found  fossil  in  Africa 
south  of  the  Sahara,  and  those  species  which  have  succeeded  in 
establishing  themselves  in  northern  Africa  have  clearly  done 
so  in  recent  geological  times.  Deer  are  absent  from  all  the 


*  Marsh,  0.  0.,  "  Introduction  of  Vertebrate  Life  in  America,"  p.  36. 

t  Matthew,  W.  D.,  "Osteology  of  Blastomeryx,"  p.  535. 

J  Osborn,  H.  F.,  "  Cenozoic  Mammal  Horizons,"  p.  88. 

§  Osborn,  H.  F.,  "Ten  Years  Progress  in  Palaeontology,"  p.  107. 


OBIGIN   OF   AMEKICAN   DEEK  111 

remainder  of  the  continent.  On  the  other  hand,  there  is  living 
in  Europe  and  Asia  at  the  present  time  a  genus  of  deer 
(Capreolus)  which  has  several  important  characters  in 
common  with  Odocoileus  and  its  more  primitive  South 
American  relations.  The  genus  Capreolus,  which  includes 
the  roedeer,  is  distinguished  from  all  the  other  Old  World 
deer  in  its  tele-metacarpal  front  limbs,  that  is  to  say  in  the 
possession  of  the  lower  remnants  of  the  lateral  metacarpal 
bones.  It  resembles,  as  we  already  know,  in  this  character 
the  true  American  deer.  Moreover,  as  Mr.  Eorig  *  has 
pointed  out,  this  is  not  the  only  feature  of  resemblance  be- 
tween Capreolus  and  Odocoileus.  The  antlers  of  the  former 
likewise  agree  with  those  of  the  New  World  deer,  rather  than 
with  those  of  the  Old  World.  Capreolus  has  the  backwardly 
directed  tine  of  Odocoileus,  and  lacks  the  brow  tine  of  Cervus. 
Even  in  the  period  of  renewal  of  the  antlers,  the  roedeter 
agrees  with  the  American  deer,  this  change  taking  place  in 
the  winter  months,  while  it  occurs  in  all  the  other  Old  World 
deer  in  the  spring  and  summer.  Only  three  kinds  of  roedeer 
exist  at  present.  In  Miocene  and  Pliocene  times,  however, 
France  and  Germany  were  tenanted  by  quite  a  large 
assemblage  of  tele-metacarpal  deer,  all  of  which  lacked  the 
brow  tine  like  Capreolus.  The  earlier  history  of  these  deer 
is  largely  obscured  by  the  circumstance  that  only  fragmen- 
tary parts  of  the  skeleton  are  known.  Thus  the  Miocene 
species  of  Dicrocerus,  which  is  supposed  to  be  related  to  the 
living  Cervulus,  possessed  antlers  that  can  be  almost  matched 
by  some  of  the  recent  South  American  mountain  forms  of 
Odocoileus,  whereas  other  South  American  forms  (Blasto- 
cerus)  remind  one  of  the  modern  roebuck. f 

I  venture  to  think  that  all  the  deer  of  South  America  have 
originated  from  one  or  more  ancestors  which  invaded  that 
continent  direct  from  western  Europe  in  early  Tertiary  times. 
Although  it  is  true  that  we  possess  little  palaeontological  evi- 
dence in  support  of  such  a  theory,  a  land  connection  must 
then  have  joined  Europe  with  South  America.  The  prob- 
able period  of  this  migration  from  Europe  to  South  America, 

*  Eorig,  Ad.,  "  Wachstum  des  Qeweihes,"  p.  424. 

f  Eorig,  Ad.,  "  Phylogenie  des  Cervidengeweihes,"  p.  542. 


112  ORIGIN   OF   LIFE   IN   AMERICA 

as  well  as  the  nature  of  the  land  bridge  which  enabled  the 
deer  to  reach  western  America  rather  than  the  east,  will  be 
discussed  in  one  of  the  subsequent  chapters.  Some  of  the 
more  primitive  forms  still  survive  in  South  America,  where 
they  have  now  been  pressed  into  the  mountain  regions.  The 
newer  and  more  vigorous  types  must  have  passed  into  North 
America  as  soon  as  that  continent  became  definitely  connected 
with  South  America  in  later  Tertiary  times. 

In  speaking  of  the  western  North  American  fauna,  Pro- 
fessor Osborn  *  tells  us  that  in  middle  Miocene  the  peculiarly 
American  Hyper tragulidae  disappeared,  while  the  European 
Cervidae  and  the  distinctly  American  Merycodontinae  took 
their  place.  Professor  Osborn  alludes  no  doubt  to  Palaeo- 
meryx  and  Blastomeryx  which  seem  to  have  originated  in 
southern  Europe,  and  spread  subsequently  eastward  to  India 
and  onward  to  America.  Both  apparently  became  extinct  in 
North  America  before  the  advent  of  Odocoileus  from  the 
south. 

The  other  large  hoofed  animal  I  alluded  to  as  frequenting 
the  lower  slopes  of  the  Rocky  Mountains  is  one  of  the  most 
peculiar  creatures  in  existence.  It  is  so  different  from  other 
animals  that  it  occupies  the  exclusive  position  of  being  the 
solitary  member  of  a  distinct  family.  Known  among  zoo- 
logists as  the  "prong -horn"  (Antilocapra  americana),  and 
among  hunters  as  the  "  antelope,"  this  splendid  animal 
possesses  the  graceful  movements  of  the  latter,  while  its  horns 
have  a  superficial  resemblance  to  the  antlers  of  a  deer.  There 
is  not  the  least  real  likeness,  however,  between  the  antlers 
of  the  prong-horn  and  those  of  a  deer,  for  they  are  not  solid, 
but  hollow  like  the  horns  of  a  goat.  The  horn  -sheaths,! 
like  the  antlers  of  a  deer,  are  shed  and  reproduced  at  regular 
intervals.  The  prong -horn  ranges  from  eastern  Mexico  to 
Saskatchewan  in  Canada  and  from  the  Missouri  River  in  the 
east  to  the  Cascade  Mountains  of  Oregon  in  the  west.  Hence 
it  is  now  a  peculiarly  western  species,  while  it  had  crossed 
the  Mississippi  during  the  Pleistocene  Period,  and  roamed 
about  Illinois  and  Wisconsin.  The  closely-allied  extinct 
genus  Merycodus  (Cosoryx)  made  its  first  appearance  in  the 

*  Osborn,  H.  F.,  "  Cenozoic  Mammal  Horizons,"  p.  77. 


PRONG-HOEN   ANTELOPE  113 

"  Deep  Eiver "  deposits  of  Montana  in  middle  or  lower 
Miocene,  and  persisted  until  the  Pliocene.  During  the  latter 
period  several  new  genera,  viz. :  Capromeryx,  Platatherium 
and  Leptotherium,  branched  off  from  the  ancestral  stock,  and 
made  their  way  into  newly-opened  areas.  The  last  two  have 
occurred  in  recent  beds  in  Brazil,  the  other  in  Nebraska. 
Thus  the  family  Antilocapridae  to  which  the  recent  prong- 
horn  and  all  these  fossils  belong,  originated  in  America  and 
never  left  it. 

Among  the  birds  of  the  Bocky  Mountains  the  dippers  are 
very  characteristic.  They  are  quite  unrepresented  on  any 
of  the  eastern  mountain  systems,  being  also  absent  from 
Greenland  and  Labrador.  In  the  Old  World  they  are  more 
or  less  confined  to  the  mountains,  but  not  nearly  to  the  same 
extent  as  in  America.  In  my  "  European  Animals  "*  I  have 
already  cited  Dr.  Stejneger's  interesting  article  on  the  geo- 
graphical distribution  of  the  dippers  (Cinclus),  and  I  may 
again  briefly  summarise  the  results  of  his  studies.  He  places 
the  origin  of  the  genus  on  the  great  plateau  adjoining 
northern  India.  At  the  dawn  of  the  Tertiary  Era  the  species 
radiated  from  this  centre  east  and  west.  America  b'eing  then 
connected  by  land  with  northern  Asia,  the  ancestors  of  the 
present  dippers  had  special  facilities  for  crossing  to  the  New 
World  from  Asia.  They  are  supposed  to  have  spread  since 
along  the  Bocky  Mountains  and  Andes  to  the  very  furthest 
end  of  South  America.  Dr.  Stejneger's  theoryf  certainly  ex- 
plains the  existing  range  of  Cinclus  in  a  satisfactory  manner, 
but  there  seems  to  me  still  another  view  of  looking  at  the 
problem.  If,  as  I  believe,  the  Atlantic  Ocean  was  bridged 
over  by  land  in  the  direction  of  southern  Europe  in  early 
Tertiary  times,  it  is  possible  that  the  dippers  may  have  been 
introduced  into  the  New  World  in  that  manner.  At  any  rate, 
the  problem  is  worth  considering  from  that  point  of  view, 
when  the  dippers  come  to  be  worked  ou,t  in  -a  thoroughly 
systematic  way.  Among  the  older  forms  of  both  animals  and 
plants  there  are  in  western  America  a  surprisingly  large 
number  of  groups  which  are  closely  related  to  European  ones. 

*  Scharff,  E.  F.,  "European  Animals,"  p.  200. 

t  Stejneger,  L.,  "  Geographical  Distribution  of  Cinclus,"  p.  425. 

L.A.  I 


114  ORIGIN  OF  LIFE   IN  AMEEICA 

In  a  later  chapter  I  shall  mention  many  of  these.  I  would 
only  here  draw  attention  to  a  striking  botanical  example 
which  seems  to  me  due  to  direct  migration  from  Europe  to 
western  North  America  and  not  by  way  of  Bering  Strait. 

Anemones  are  so  much  cultivated  now  in  gardens  that 
almost  everyone  is  familiar  with  them.  Their  geological 
history  no  doubt  has  been  a  very  remarkable  one.  Not  a 
single  fossil  anemone  is  known  to  science,  because  the  plant 
contains  no  part  that  might  readily  be  preserved,  and  yet  it 
can  be  asserted  that  the  genus  must  have  originated  in  very 
remote  times.  The  occurrence  of  many  species  in  isolated 
mountain  regions,  the  extremely  discontinuous  and  wide 
range  of  others,  and  especially  the  high  percentage  pf 
endemism,  clearly  imply  that  we  have  to  deal  with  an  ancient 
genus.  Dr.  Ulbrich,*  to  whom  we  are  indebted  for  a  splendid 
monograph  of  the  genus  Anemone,  is  of  opinion  that  some 
of  its  sections  were  already  developed  in  early  Tertiary  times. 
His  view  is,  of  course,  entirely  derived  from  what  we  might 
call  circumstantial  evidence,  just  as  Dr.  Stejneger's  was  in 
regard  to  the  age  of  the  genus  Cinclus.  One  of  these  species 
of  anemone  (A.  baldensis),  a  well-known  alpine  plant,  is, 
according  to  Dr.  Ulbrich,  probably  of  Miocene  age.  It  grows 
also  in  the  Carpathians,  the  Apennines,  the  Pyrenees  and 
northern  Spanish  Mountains,  but  nowhere  in  Asia.  Never- 
theless, the  same  species  occurs  in  the  highest  elevations  of 
the  Sierra  Nevada  in  California,  in  the  Cascade  and  Bocky 
Mountains.  A  very  closely-allied  form  of  anemone  (A.  teto- 
nensis)  lives  at  a  height  of  over  10,000  feet  in  Idaho,  and 
another  (A.  jamesoni)  at  about  the  same  elevation  in  the 
Andes  of  Ecuador.  All  these  nearly  related  forms,  there- 
fore, are  confined  to  Europe  and  western  America. 

Among  all  the  older  American  forms  both  of  animals 
and  plants,  other  possible  routes  of  migration  besides  the 
Bering  Strait  one  have  to  be  taken  into  consideration.  Be- 
turning  to  the  birds  again,  it  seems  to  me  that  the  genus 
Begulus  to  which  the  European  golden-crested  wren  belongs, 
must  have  entered  North  America  in  Pliocene  times  along 
with  the  great  mammals  alluded  to  in  the  last  chapter.  In 

*  Ulbrich,  E.,  "  Qeograph.  Verbreitung  d.  Gattung  Anemone,"  p.  325. 


ROCKY  MOUNTAIN  PLANTS        115 

North.  America  we,  have  Regulus  cuvieri,  only  one  specimen 
of  which  is  known,  Regulus  satrapa  and  Regulus  calendula. 
None  of  these  have  succeeded  in  penetrating  southward 
beyond  Guatemala  in  Central  America,  the  genus  having  a 
wide  range  on  the  continent.  Hence  it  is  reasonable  to 
suppose  that  the  ancestors  of  Begulus  invaded  North  America 
from  Asia  by  way  of  the  Bering  Strait  land  connection. 

Among  the  invertebrates  of  the  Rocky  Mountains  the 
beetles  and  butterflies  are  probably  the  best-known  groups. 
They  may  be  considered  by  some  as  of  little  importance  in  the 
solution  of  such  problems  as  we  have  been  dealing  'with,, 
because  these  insects  are  generally  believed  to  be  very  liable 
to  accidental  dispersal.  One  of  the  most  powerful  distri- 
buting agents  of  insects  subject  to  accidental  dispersal  is  no 
doubt  the  wind.  Nevertheless  many  naturalists,  who  have 
made  a  serious  study  of  the  geographical  distribution  of 
animals  and  plants,  have  come  to  the  conclusion  that  neither 
wind  nor  other  agencies  of  accidental  dispersal  are  of  such 
paramount  importance  as  we  are  often  led  to  believe.  The 
species  of  a  genus,  even  of  butterflies  or  beetles,  as  a  rule', 
are  clustered  round  a  centre  from  which  we  can  easily 
imagine  them  to  have  been  slowly  dispersed  in  the  course 
of  time.  Usually  we  can  trace  an  intimate  relationship 
between  the  species  whose  areas  of  distribution  adjoin 
one  another.  The  conditions  of  dispersal,  in  fact,  even 
among  winged  insects,  must  be  quite  similar  to  those 
with  which  we  are  acquainted  among  the  higher  mam- 
mals. The  latter  spread  gradually  on  land  from  their 
centre  of  origin.  Sometimes  we  meet  with  allied  groups 
of  species  among  beetles  and  butterflies  whose  ranges  are 
separated  by  extremely  wide  areas  in  which  no  near  relations 
occur.  We  might  be  tempted  to  attribute  such  instances  to 
accidental  dispersal  by  wind.  We  might  suppose  that  an 
exceptionally  powerful  storm  had  carried  these  frail  insects 
a  few  thousand  miles  away  to  a  spot,  where  on  alighting  they 
found  the  conditions  for  their  future  development  favourable. 
When  similar  cases  of  distribution  occur  among  mammals 
they  are  explained  in  a  different  manner.  We  then  argue 
that  the  related,  but  now  widely  separated  or  "  discontinuous," 
groups  must  long  ago  have  had  a  perfectly  continuous  range 

i2 


116  ORIGIN   OF   LIFE    IN   AMERICA 

and  that  for  some  reason  or  other  they  have  subsequently 
been  destroyed  over  wide  areas,  leaving  at  present  only  iso- 
lated colonies.  In  some  instances  this  theory  of  the  origin 
of  discontinuous  colonies  of  animals  has  been  amply  con- 
firmed by  fossil  evidence.  Camels,  for  example,  or  we  might 
say  the  family  Camelidae  to  which  they  belong,  are  only 
represented  in  South  America  and  Asia ;  but  since  numerous 
fossil  members  of  the  family  occur  in  North  America, 
we  possess  decisive  evidence  that  long  ago  the  range  of 
the  camel  family  was  continuous.  Discontinuity  of  range 
among  mammals  is  always  looked  upon  by  zoologists  as 
an  unmistakable  sign  of  antiquity.  It  is  only  when  a 
similar  range  occurs  among  the  more  easily  dispersed  in- 
vertebrates and  plants  that  naturalists  are  in  the  habit 
of  calling  to  aid  exceptional  forces  of  nature  in  explaining 
their  origin.  The  undoubted  facility  with  which  human 
importations  are  scattered  far  and  wide  and  become  success- 
fully .established  in  districts  remote  from  their  original 
home  seems  to  encourage  and  invite  speculations  as  to 
the  origin  of  dis continuously  distributed  invertebrates  of 
all  kinds.  Actual  records  of  seeds,  insects,  snails,  etc.,  sowed 
broadcast  by  accidental  agencies  far  from  their  native 
land,  appear  to  confirm  the  theories  derived  from  successful 
human  transplantations.  So  much  are  these  in  vogue  that 
the  ordinary  and  normal  mode  of  dispersal  is  almost  for- 
gotten. Winds  no  doubt  exert  an  influence  in  driving  species 
in  the  direction  in  which  they  blow.  But  many  animals, 
beasts  as  well  as  beetles  or  butterflies,  possess  the  faculty 
in  a  high  degree  of  detecting  the  presence  of  their  own  kind 
by  the  sense  of  smell.  Winds  would,  and  do,  as  we  know, 
convey  scents  from  one  animal  to  another,  thus  tending  to 
bring  the  sexes  together.  This  has  been  very  clearly  estab- 
lished by  Mr.  Webster.*  The  insect,  being  apprised  by  scent 
of  the  presence  of  its  own  kind,  would  endeavour  to  travel 
in  the  direction  contrary  to  that  of  .the  prevailing  wind  in 
order  to  reach  it.  It  may  possibly  be  true  that  some  insects 
are  apt  to  spread  in  the  direction  of  the  prevailing  wind,  as 
Mr.  Webster  asserts.  But,  judging  from  the  few  examples 

*  Webster,  F.  M.,  "Diffusion  of  Insects,"  p.  797. 


DISPERSAL  OF.  BUTTERFLIES  117 

he  quotes,  I  do  not  think  there  is  sufficient  evidence  for  the 
belief  that  insects  as  a  whole  are  influenced  in  their  dispersal 
by  that  agency.  His  statement  that  the  influence  of  high 
winds  on  insects  is  illustrated  by  the  great  number  of  butter- 
flies that  are  sometimes  encountered  by  ships  at  sea  at  long 
distances  from  land,  is  somewhat  misleading.  As  a  matter 
of  fact,  remarkably  few  species  of  butterflies  have  been 
observed  far  out  at  sea,  and  these  always  belong  to  species 
that  are  in  the  habit  of  migrating.  It  is  a  well-known 
phenomenon  that  certain  species  of  butterflies  and  moths, 
such  as  the  painted  lady  (Vanessa  cardui),  the  milk- weed 
butterfly  (Anosia  archippus)  and  the  moth  Urania  leilus, 
congregate  into  flocks  or  swarms  and  migrate  in  a  body  at 
certain  times  of  the  year.  And  it  is  such  swarms  that  are 
occasionally  scattered  by  storms  and  carried  out  to  sea. 
These  are,  however,  altogether  exceptional  instances,  and  we 
are  not  justified  in  drawing  conclusions  from  them  and  apply- 
ing them  to  insects  as  a  whole,  very  few  of  which  possess  any 
migrating  instincts. ,  On  the  contrary,  the  facts  of  the 
geographical  distribution  of  insects  are,  as  a  rule,  quite 
in  conformity  of  thpse  of  mammals.  Even  the  distribu- 
tion of  the  strongly- winged  Sphingidae  in  North  America 
shows  a  distinct  division  into  an  Atlantic  and  Pacific  sub- 
region. 

I  have  already  alluded,  on  p.  90,  to  the  range  of  the  genus 
of  butterflies  Parnassius  in  North  America,  pointing  out  that 
it  had  apparently  entered  the  continent  in  Alaska  and  had 
then  spread  along  the  Eocky  Mountain  chain.  Altogether,  the 
butterflies  and  moths  of  the  Rocky  Mountains  show  a  close, 
resemblance  to  those  of  the  Old  World ;  among  them  we  meet 
with  the  familiar  genera  Colias,  Argynnis,  Erebia  and 
Oeneis.*  The  main  advance  has  apparently  taken  place  in  a 
southward  direction  from  the  north  along  the  crest  of  the 
mountains. 

Much  remains  to  be  done  before  we  can  obtain  even  a 
general  idea  of  the  beetle  fauna  of  the  Rocky  Mountains,  but 
it  is  certain  that  many  Old  World  genera  and  even  species, 
have  travelled  southward  along  this  chain  for  a  considerable 

*  Pagenstecher,  A.,  "  Lepidopteren  d.  Hochgebirges,"  p.  145. 


118  ORIGIN  OF   LIFE  IN   AMERICA 

distance.  On  the  other  hand,  typically  American  genera,  like 
the  oil  beetles  (Eleodes),  have  gained  access  to  heights  up  to 
8,000  feet  in  the  southern  spurs  of  the  Rocky  Mountains. 

Of  fossil  insects,  in  spite  of  Mr.  S.  H.  Scudder's  *  classic 
researches  and  Dr.  Handlirsch's  splendid  treatise,  we  know 
comparatively  little.  But  our  knowledge  has  been  particularly 
enriched  by  the  discovery,  in  the  midst  of  the  Rocky  Mountains 
of  a  deposit  of  shales  containing  a  wealth  of  the  most  beauti- 
fully preserved  specimens  of  insects  and  plants.  During  one 
of  the  volcanic  eruptions,  which  were  so  frequent  in  Tertiary 
times  throughout  the  greater  part  of  the  Rocky  Mountains 
region,  great  masses  of  leaves  and  innumerable  insects  were 
entombed  among  the  fine  volcanic  ash,  and  were  thus  readily 
preserved.  Over  six  hundred  species  of  insects  are  now  known 
from  these  Florissant  shales  of  Colorado,  which,  according  to 
Professor  Cockerell  f  are  not  of  Oligocene  age,  as  Mr.  Scudder 
thought,  but  of  Miocene  age.  The  absence  of  mammalian 
remains,  however,  increases  the  difficulty  of  estimating  the 
exact  age  of  these  deposits.  It  is  possible,  moreover,  that  some 
of  the  shales  may  be  much  older  than  others. 

I  cannot  leave  the  Rocky  Mountains  without  expressing  a 
few  words  of  appreciation  as  to  the  wisdom  and  forethought 
of  the  Americans  in  preserving  large  tracts  of  country  in  the 
wild  state.  These  large  land  reserves,  as  Mr.  Roosevelt  $  so 
•forcibly  reminds  us,  are  mainly  to  keep  the  forests  from 
destruction,  but  likewise  to  preserve,  for  future  generations, 
the  wild  animals  that  live  in  them. 

The  first  and  most  fa/mous  game  preserve  in  the  world  was 
established  in  1872  and  set  apart  as  a  public  park  or  pleasure 
ground  for  the  benefit  and  enjoyment  of  the  people.  Congress 
provided  against  the  wanton  destruction  of  fish  and  game,  or 
their  capture  or  destruction  for  merchandise  or  profit.  As  a 
result  of  this  wise  enactment  we  find  to-day  thousands  of 
deer  of  various  kinds  in  this  magnificent  world-famed  en- 
closure known  as  the  "  Yellowstone  Park,"  the  name  being 
derived  from  Yellowstone,  the  largest  tributary  of  the  Missouri 

*  Scudder,  S.  H.,  "  Tertiary  Insects  of  North  America." 

t  Cockerell,  T.  D.  A.,  "  Fauna  and  Flora  of  Florissant,"  p.  160. 

|  Eoosevelt,  Th.,  "  Wilderness  Eeserves,"  pp.  23—24. 


NATIONAL  GAME   PEE  SERVES  119 

River.  I  need  not  enlarge  upon  the  fascinating  spectacles  of 
the  hot  springs  or  the  geysers,  waterfalls  and  other  natural 
wonders  which  attract  sightseers  to  this  district. 

Since  the  opening  of  the  Yellowstone  Park,  largely  owing 
to  the  efforts  of  the  Boone  and  Crockett  Club  and  its  founder 
Mr.  Theodore  Koosevelt,  many  other  game  and  forest  pre- 
serves have  been  established  in  the  United  States.  The 
American  Bison  Society  and  the  New  York  Zoological  Society 
also  worked  incessantly  towards  the  same  end,  so  that  at  pre- 
sent ove'r  seven  million  acres  in  the  United  Staites  are  devoted 
to  the  preservation  of  the  native  fauna  and  flora.  The  two 
largest  enclosures  are  Ihe  Yellowstone  Park  in  Wyoming,  and 
the  Grand  Canon  Game  Preserve  in  Arizona.  This  growth  of 
sentiment  in  favour  of  protecting  animals  and  plants  from 
destruction  has  also  spread  beyond  the  borders  of  the  States 
into  Canada,  and  induced  the  authorities  there  to  imitate  these 
beneficent  measures.  In  their  enthusiasm  to  vie  with  their 
neighbours,  Canadians  have  even  provided  game  preserves 
which  exceed  in  size  the  largest  of  those  referred  to,  for  the 
new  Jasper  Park  in  Alberta  has  an  area  of  nearly  three  and  a 
half  million  acres,  while  Kocky  Mountain  Park  in  Alberta 
has  two  million  seven  hundred  thousand  acres.  Two  others 
have  over  a  million  acres. 

Hidden  game  preserves  of  the  past  life  of  North  America, 
as  I  mentioned  before,  lie  among  the  vast  accumulations  of 
Tertiary  rocks  in  the  same  mountains  that  shelter  the  modern 
representatives  of  the  American  fauna.  In  the  beginning  of 
the  chapter  I  just  alluded  to  the  names  of  some-  of  the  more 
important  deposits  and  the  geological  formations  they  belong 
to.  Enough  is  now  known  of  the  remains  of  the  animals  con- 
tained in  these  deposits  to  enable  palaeontologists  to  compare 
their  relationship  with  that  of  fossil  assemblies  of  animals  in 
other  continents.  Professor  H.  F.  Osborn  has  recently  pub- 
lished an  excellent  summary  of  our  knowledge  of  these  western 
beds  and  their  mammalian  fauna,  and  I  cannot  do  better  than 
quote  some  of  his  conclusions. 

The  Eocene  Tertiaries  of  the  mountain  region,  lying  in  the 
Rockies  and  west  of  them,  were  partly  formed  by  the  post- 
Cretaceous  or  post-Laramie  uplift,  accompanied  by  great 
volcanic  activity,  lava  flows  and  eruptions  of  volcanic  dust,  and 


120  OBIGIN  OF  LIFE   IN  AMERICA 

by  the  formation  of  a  series  of  lake,  river  and  flood -plain 
basins,  filled  with  volcanic  and  erosion  sediments.  During 
the  first  faunal  phase  of  the  Eocene  Period  a  land  connec- 
tion with  South  America  seems  to  be  indicated  by  the  occur- 
rence of  similar  mammals  in  the  upper  Cretaceous  or  basal 
Eocene  of  Patagonia.  Additional  evidence  of  South  American 
connection  is  afforded  by  the  subsequent  occurrence  of  animals 
related  to  the  Edentata-Dasypoda  in  the  American  middle 
Eocene.  A  momentous  change  occurs,  according  to  Professor 
Osborn,  during  the  second  faunal  phase  of  the  Eocene. 
Similar  faunas  appear  almost  simultaneously  in  south -western 
North  America  and  in  western  Europe.  In  Professor 
Osborn's  *  judgment  this  remarkable  circumstance  is  due  to 
the  gradual  southward  extension  of  the  fauna  from  a  hypo- 
thetical northerly  American- Asiatic  land  mass. 

Not  a  single  specimen  of  an  Eocene  mammal  has  been  dis- 
covered in  northern  Asia  or  the  northern  parts  of  North 
America.  Professor  Osborn  and  many  other  authorities 
assume  the  Eocene  existence  of  a  great  American- Asiatic 
land  mass,  because  large  tracts  of  land  in  the  north  certainly 
are  very  ancient,  and  must  have  been  raised  above  the  sea  in 
Eocene  times.  That  is  about  all  the  evidence  we  possess 
for  the  belief  that  the  great  similarity  of  the  western  European 
and  western  North  American  fauna  during  the  Eocene  Period 
was  due  to  some  land  connection  via  northern  Asia  and 
northern  North  America. 

I  should  prefer  to  throw  my  hypothetical  land  bridge 
straight  across  the  Atlantic  from  western  Europe  'to  North 
America.  In  another  chapter  I  shall  endeavour  to  show  that 
we  possess  important  zoogeographical  evidence  for  the  belief 
in  such  a  transatlantic  bridge  in  Eocene  times.  Professor 
Schlosserf  contends  that  geological  researches  are  alone 
capable  of  yielding  information  about  former  land  connec- 
tions. He  does  not  believe  that  much  weight  can  be  attached 
to  ancient  reconstructions  of  continents  based  on  zoogeo- 
graphical or  distributional  data.  I  hold,  on  the  contrary,  that 
since  certain  old  groups  of  animals,  even  genera  and  species, 

*  Osborn,  H.  F.,  "  Cenozoic  Mammal  Horizons,"  pp.  19 — 35. 

t  Schlosser,  M.,  "Uber  Tullberg's  System  der  Nagetiere,"  p.  748. 


DEPOSITS  OF  THE   TERTIARY  ERA          121 

have*  originated  in  the  far  distant  past  and  are  now  scattered 
here  and  there  in  isolated  colonies,  their  present  range  indi- 
cates former  conditions  of  land  and  water.  By  comparing 
the  discontinuous  distribution  of  such  old  groups  in  the  dif- 
ferent continents,  we  come  to  certain  conclusions  as  to  the 
conditions  of  the  continents  during  the  time  when  their  range 
was  continuous.  We  have  already  become  acquainted  with 
several  genera  and  species  showing  discontinuous  distribu- 
tion. I  argued,  in  the  first  and  fourth  chapters,  mainly  from 
distributional  evidence,  that  North  America  was  connected 
with  north-western  Europe  and  with  north-eastern  Asia  in 
Pliocene  times.  We  know  of  relict  genera  and  species  which 
represent  the  life  and  the  geographical  conditions  of  still 
more  remote  stages  of  the  Tertiary  Era,  namely,  the  Miocene, 
Oligocene  and  Eocene,  and  even  periods  of  the  secondary  or 
Mesozoic  ^Era.  We  thus  possess  in  our  recent  fauna  an  invalu- 
able adjunct  to  palaeontological  research.  That  this  state- 
ment is  not  a  mere  assumption  will  be  amply  demonstrated  in 
the  next  few  chapters. 

Returning  to  Professor  Osborn's  researches,  he  directs  at- 
tention to  the  striking  diminution  of  European  types  in  the 
last  stages  of  the  Eocene  deposits.  This,  he  argues,  might 
have  been  due  to  the  existence  of  prolonged  geographic  or 
climatic  barriers  between  the  two  continents.  In  Oligocene 
times  the  faunal  community  with  western  Europe  once  more 
becomes  closer.  It  is  important  to  note,  Professor  Osborn  re- 
marks, that  many  American  lower  Oligocene  types  are  repre- 
sented by  more  primitive  forms  of  European  upper  Eocene  and 
partly  of  north  African  types.  This  stage  is  followed  by  a  long 
period  of  independent  evolution  and  partial  extinction  of  the 
same  fauna  to  the  close  of  the  lower  Miocene  age.  About  the 
middle  of  the  Miocene  Period  another  profound  change  in 
the  mammals  of  North  America  occurs.  This  is  mainly  due  to 
the  .sudden  appearance  of  a  large  number  of  new  forms  of 
African  and  Eurasiatic  origin,  such  as  the  elephants,  which 
are  believed  to  have  come  from  Africa,  and  the  rhinoceroses 
and  the  true  ruminant  animals,  which  are  supposed  to  have 
had  their  home  in  Asia  or  Europe-.  These  North  American 
middle  Miocene  deposits  contain  animals  which  first  appear 
in  the  lower  Miocene  of  Europe.  Hence  there  is  distinct  evi- 


122  OKIGIN  OF   LIFE   IN  AMEKICA 

dence  for  the  assumption  that  the  general  movement  of  the 
fauna  has  been  from  the  Old  World  to  the  New.  Finally, 
in  the  Pliocene  beds  of  North  America,  we  perceive  clearly 
that  an  invasion  of  South  American  animals  has  taken 
place.* 

*  Osborn,  H.  F.,  "  Cenozoic  Mammal  Horizons,"  pp.  42 — 82. 


CHAPTER  VI 

ANIMALS  OF  THE  EASTERN  STATES 

WHEN  a  naturalist  from  western  Europe  crosses  the  Atlantic, 
and  after  landing  at  one  of  the  great  ports  on  the  east  coast 
of  the  United  States,  takes  a  stroll  in  the  country  on  a  fine 
summer's  day,  a  great  many  novel  features  strike  his  eye. 
Let  us  suppose,  for  instance,  that  he  is  specially  interested 
in  reptiles  and  amphibians.  Although  the  neighbourhood  of 
New  York  and  Boston  abounds  with  ideal  dry  sandy  banks 
which  would  be  alive  with  lizards  if  situated  in  France  or 
Germany,  these  reptiles  seem  to  be  completely  absent.  This 
is  actually  the  case.  No  lizards  have  been  observed  in  the 
neighbourhood  of  these  cities.  If  he  went  further  inland 
to  ascertain  whether  America  is  really  devoid  of  lizards,  our 
visitor  might  succeed,  after  crossing  the  Hudson  Eiver,  in 
capturing  some.  Two  kinds  of  lizard  have  been  recorded 
from  the  western  parts  of  the  State  of  New  York,  viz.,  the 
blue-tailed  lizard  (Eumeces  quinquelineatus)  and  the  common 
swift  (Sceloporus  undulatus).*  The  first  of  these  is  a  strik- 
ingly handsome  species  with  five  vividly  yellow  lines  along 
the  back  and  a  tail  of  brilliant  blue.  It  is  altogether  different 
from  the  ordinary  European  lizards,  for  the  scales  are  shiny 
like  those  oif  the  slow-worm.  "The  blue-tailed  lizard  forms 
part,  in  if  act,  of  the  large  family  of  skinks  (Scincidae)  most 
o'f  which  inhabit  the  tropical  portions  of  the  Old  World.  The 
genus  Eumeces  (Plestiodon)  to  which  the  American  blue- 
tailed  lizard  belongs,  is  largely  confined1  to  the  south-eastern 
and  southern  States  of  North  America.  A  few  species  are 
found  in  the  south-west  and  in  Mexico,  while  the  genus  is 
entirely  absent  from  South  America  and  Europe.  Eight 
species  are  known  from  Asia.  Now  the  most  remarkable  point 

*  Eckel,  E.  C.,  and  F.  0.  Paulmier,  "  New  York  Keptiles,"  p.  390. 


124  ORIGIN   OF   LIFE   IN  AMERICA 

about  this  blue-tailed  skink  is  that  a  species,  until  recently 
considered  absolutely  identical  with  it,  is  found  in  Japan, 
being  unknown  on  the  mainland  of  Asia.  Some  differences 
have  now  been  detected  between  these  two  skinks,  but  they 
are  no  doubt  very  closely  related  to  one  another.  We  are  con- 
ironted,  therefore,  with  the  extraordinary  problem  how  to 
account  for  the  occurrence  of  two  species,  so  nearly  akin, 
in  localities  so  distant  from  one  another.  It  must  be  clear  to 
anyone  who  is  familiar  with  distributional  problems  that  acci- 
dental dispersal  within  recent  times  either  by  man  or  by 
any  other  agency  is  out  of  the  question.  This  is  a  case  of 
geographical  distribution  which  must  be  explained  by  the 
ordinary  modes  of  migration.  If  it  was  quite  a  unique 
instance  of  such  a  remarkably  discontinuous  range,  it  might 
be  a  matter  of  some  difficulty  to  discover  a  plausible  explana- 
tion to  account  for  it.  But  it  is  by  no  means  the  only  example 
of  such  a  range.  Quite  a  number  of  instances  are  known.  A 
still  more  striking  one  is  that  of  the  so-called  ground  lizard 
(Lygosoma  laterale).* 

The  ground  lizard,  with  its  minute  limbs,  thick  tail  arid 
sluggish  movements,  reminds  one  more  of  a  salamander  than 
a  lizard.  It  lives,  moreover,  under  the  bark  of  trees  or  among 
rotten  wood,  and  is  thus  altogether  different  in  habits  from 
the  ordinary  lizard.  Now  this  peculiar  ground  lizard  occurs 
in  identically  the  same  form  in  North  America,  in  China  and 
Japan. f  The  most  searching  comparison  by  the  best  experts 
has  hitherto  failed  to  elicit  the  slightest  difference  between 
the  Asiatic  and  this  North  American  ground  lizard. 

It  is  interesting  to  note  that  the  ground  lizard  and 
the  blue-tailed  lizard,  both  of  which  exhibit  such  a  remark- 
ably East  Asiatic  relationship,  are  members  of  the  family 
Scincidae.  But,  whereas  we  possess  in  America  over  thirty 
species  of  the  genus  Eumeces,  to  which  the  blue-tailed 
lizard  belongs,  there  are  only  two  American  species  of 
Lygosoma.  We  now  have  to  ascertain  whether  these  two 
genera  Eumeces  and  Lygosoma,  are  of  American  origin,  or 

*  Cope,  E.  D.,  "  Crocodilian®,  lizards  and  snakes  of  North  America," 
p.  622. 

f  Stejneger,  L.,  "  Herpetology  of  Japan,"  p.  219. 


LIZARDS   OF    THE   EASTERN    STATES         125 

whether  they  have  come  to  America  from  some  other  part 
of  the  world.  Lygosoma  laterale  is  known  from  eastern 
Mexico  in  the  south-west,  and  from  all  the  southern  and 
eastern  States  as  far  north  as  New  Jersey.  Altogether  fifty 
species  of  the  division  of  Lygosoma,  to  which  the  American 
species  belong,  have  been  described.*  Five  of  them  live  in 
New  Zealand,  twenty  in  Australia  and  the  adjacent  islands, 
seven  in  the  Pacific  Islands,  four  in  the  Philippines  and 
Borneo,  seven  in  India,  two  in  the  Nicobar  Islands,  one  in 
Mauritius,  two  in  West  Africa,  one  in  Central  America,  while 
a  single  species,  as  far  as  we  have  learnt,  is  found  in  China, 
Japan  and  North  America.  The  wide  range  of  the  species  in 
North  America  shows  that  it  has  not  been  introduced.  It  is 
no  doubt  indigenous.  Yet,  to  judge  from  the  range  of  the 
genus  Lygosoma,  America  is  certainly  not  its  home.  We  may 
also  safely  conclude,  from  its  most  discontinuous  range,  that 
it  is  of  very  great  antiquity,  although  quite  unknown  as  a 
fossil.  New  Zealand,  according  to  Dr.  Wallace,f  received  its 
flora  and  fauna  during  the  latter  part  of  the  Secondary  Era, 
and  has  not  since  been  connected  with  any  mainland.  Since 
this  view  has  been  widely  accepted,  it  would  tend  to  show 
that  the  genus  Lygosoma  w,as  already  in  existence  in 
Mesozoic  times,  and  that  it  possibly  gained  its  present 
distribution  towards  the  end  of  the  Secondary  or  early  in 
the  Tertiary  Era. 

The  second  genus  Eumeces  may  help  us  in  our  enquiry 
as  to  the  mode  of  entry  into  North  America.  There  are  about 
twenty  species  of  Eumeces  in  North  America,  ranging  from 
Mexico  in  the  south  to  Minnesota  in  the  north,  and  New 
Jersey  in  the  east.  Considerably  over  one-half  of  these  inhabit 
the  south-western  States  and  Mexico.  Certainly  the  centre 
of  distribution  in  America  lies  in  the  south-west.  The  various 
species  seem  to  have  radiated  from  this  centre  in  all  directions 
except  the  south.  The  genus  must  have  existed  in  this  south- 
western centre  for  a  very  long  time  past,  because  one  species 
peculiar  to  an  island  in  the  Bay  of  Campeche,  another  to  the 
Island  of  Bermuda,  and  still  another  to  southern  Florida,  are 

*  Boulenger,  G.  A.,  "  Catalogue  of  Lizards,"  Vol.  III.,  pp.  253—289. 
t  Wallace,  A.  K,  "  Island  Life,"  p.  506. 


126  ORIGIN   OF   LIFE   IN   AMERICA 

known  to  science.  Eumeces  must  have  lived  in  North 
America  possibly  since  early  Tertiary  times.  The  genus  has 
also  been  observed  in  India.  One  of  the  species  ranges  from 
Baluchistan,  right  through  Persia,  Syria  and  Egypt  to  Tunis, 
having  there  probably  given  rise  to  the  allied  form  confined 
to  Algeria  and  Morocco. 

If  Eumeces  had  already  existed  in  south-western  North 
America  in  early  Eocene  times,  we  should  expect  it  to  have 
travelled  to  South  America  during  the  supposed  Eocene  land 
connection  with  that  continent.  That  it  has  not  done  so  may 
be  due  to  the  fact  that  its  original  home  is  in  south-eastern 
Asia.  This  assumption  is  strengthened  by  the  circumstances 
that  its  nearest  relations  are  the  genera  Tribolonotus  of  New 
Guinea,  and  Brachymeles  of  the  Philippine  Islands. 

Since  Lygosoma,  like  Eumeces,  also  occurs  in  the  south- 
western States,  it  may  likewise  have  made  its  entry  into  North 
America  in  that  region,  though  its  original  home  seems  to  have 
been  somewhere  in  the  western  Pacific.  Being  probably  an 
older  genus  than  Eumeces,  both  may,  nevertheless,  have  taken 
the  same  route  in  reaching  North  America.  Where  that  route 
lay  and  what  were  the  geographical  features  of  North  America 
at  the  time  will  be  discussed  later  on  when  more  material  has 
been  gathered  from  other  sources. 

I  alluded  above  to  another  lizard  which  has  penetrated  as 
far  north  as  New  Jersey,  namely,  the  swift  (Sceloporus  undu- 
latus) ,  so  called  from  the  great  activity  and  speed  of  its  move- 
ments.* Its  scales  are  strikingly  different  from  those  of  the 
skinks.  They  are  large  and  coarsely  keeled,  terminating  in 
sharp,  bristly  points.  The  swifts  belong  to  the  typically 
American  family  Iguanidae.  All  the  Iguanidae,  and  there  are 
many  of  them,  are  confined  to  North  and  South  America,  with 
the  exception  of  one  genus  which  inhabits  the  Fiji  Islands 
and  two  others  living  in  Madagascar.  It  is  quite  possible, 
however,  as  Dr.  Gadowf  suggests,  that  the  Madagascar  genera 
represent  cases  of  convergent  evolution  from  some  common 
ancestor. 

Although  a  species  of  Iguana  has  been  described  from  the 

*  Ditmars,  E.  L.,  "  The  Eeptile  Book,"  p.  123. 
t  Gadow,  H.,  "  Amphibia  and  Keptiles,"  p.  501. 


SNAKES  OF  THE  EASTERN  STATES    127 

Eocene  deposits  of  France  and  England,  we  have  no  reason 
to  doubt  that  the  family  has  originated  in  America.  The 
Cretaceous  genera  Iguanavus  and  Chamops  from  Wyoming, 
have  always  been  considered  as  belonging  to  the  Iguanidae. 
Since  the  family  scarcely  enters  eastern  America  even  at  the 
present  day,  the  western  States  must  always  have  been  its 
headquarters.  How  the  dispersal  from  the  American  con- 
tinent to  the  Fiji  Islands  was  effected  is  another  problem 
which  I  defer  to  a  later  discussion. 

As  for  the  genus  Sceloporus,  to  which  the  swift  (S;.  undu- 
latus)  belongs,  almost  all  the  species  inhabit  Mexico,  that 
country  forming  the  centre  of  distribution.  From  there  the 
genus  ranges  as  far  south  as  Nicaragua,.  One  species  occurs 
in  the  western  States,  while  the  single  northern  species, 
Sceloporus  undulatus,  ranges  from  Guatemala  to  the  eastern 
States.  Both  the  nearest  relations  of  this  genus,  Phrynosoma 
and  Uta,  have  their  headquarters  in  the  south-western  States 
and  Mexico.  We  possess,  consequently,  satisfactory  evidence, 
both  from  its  recent  as  well  as  its  fossil  distribution,  that 
the  family  Iguanidae  is  of  North  American  origin,  and  that 
the  latter  can  be  traced  to  the  end  of  the  Mesozoic  Era. 

In  spite  of  the  occurrence  of  these  three  species  of  lizards 
in  some  of  the  north-eastern  States,  these  reptiles  certainly 
are  scarce  in  the  east.  It  is  not  so  with  the  snakes.  No  less 
than  twenty-three  different  kinds  have  been  observed  in  the 
vicinity  of  New  York,*  whereas  in  the  whole  of  France  there 
are  only  about  half  that  number.  The  eastern  States  of 
America  are,  in  fact,  remarkably  rich  in  snakes.  Snakes  have 
even  penetrated  to  the  eastern  islands,  for  several  species,  in- 
cluding the  dreaded  rattlesnake,  occur  in  Long  Island. 

The  commonest  of  these  eastern  and  probably  of  all  the 
American  snakes,  is  the  garter-snake  (Thamnophis  or  Eutenia 
sirtalis).  It  is  abundant  from  southern  Canada  to  Florida, 
and  I  have  met  with  it  even  on  the  edge  of  the  White  Moun- 
tains plateau  at  a  height  of  5,000  feet.  Very  closely  allied 
to,  arid  scarcely  distinct  from  the  genus  Tropidonotus,  the 
garter- snakes  (Thamnophis)  form  a  most  troublesome  group 

*  Eckel,  E.  C.,  and  F.  C.  Paulmier,  "New  York  Eeptiles,"  p.  356— 
388. 


128  ORIGIN   OF   LIFE   IN   AMERICA 

from  a  systematic  point  of  view.  Several  of  the  species  are 
exceedingly  variable,  and  all  are  difficult  to  discriminate  from 
one  another. 

The  genetic  relationships  of  the  various  species  and  the 
causes  which  have  given  rise  to  the  differentiation  of  the 
garter-snakes  are  most  attractive  subjects  for  study.  Dr. 
A.  E.  Brown*  has  discussed  the  connection  between  moisture 
and  variability,  especially  in  the  direction  of  colour  intensity 
in  this  group  of  snakes.  More  recently  an  ingenious  and 
novel  method  of  carefully  estimating  the  value  of  the  cha- 
racters commonly  held  to  be  specific  in  snakes  has  been 
adopted  by  Dr.  Ruthven.  He  shows  that  the  reductions  in  the 
number  of  rows  of  dorsal  scales  as  the  girth  ,of  the  body 
decreases  in  the  individual  snake,  are  brought  about  by  the 
dropping  of  certain  definite  rows.  This  leads  him  to  the  con- 
clusion that  specific  variation  in  the  scale  rows  follows  the 
same  sequence  and  is  also  correlated  with  the  circumference 
of  the  body.  Similarly,  presence,  absence  or  fusion  of  the 
labial  scuta  are  dependent  on  the  length  of  the  head.  Dr. 
Ruthven's  f  assumption  is  that  the  garter-snakes  started  in 
America  with  the  maximum  number  of  dorsal  rows  of  scales 
known  in  the  genus,  and  that  the  forms  resulting  from  geo- 
graphical extension  are  mostly  due  to  dwarfing  in  consequence 
of  unfavourable  environment.  He  then  traces  four  lines  of 
descent,  which  all  emanate  from  northern  Mexico  as  the  centre 
of  origin  of  the  genus.  'The  area  inhabited  by  the  nineteen 
species  of  garter-snakes  includes  all  North  America  and  south- 
ward as  far  as  the  southern  boundary  of  Guatemala.  The 
genus  is  evidently  a  geologically  recent  immigrant  to  Central 
America. 

It  is  of  the  greatest  interest  to  the  student  of  zoogeography 
that  Thamnophis  differs  from  its  nearest  American  relative, 
Tropidonotus,  by  the  absence  of  scale  pits,  and  by  the  pre- 
sence of  an  undivided  anal  plate,  for  it  seems  almost  certain 
that  Thamnophis  has  originated  in  North  America  from  some 
ancestral  form  of  Tropidonotus  (Natrix),  the  latter  being 
clearly  a  much  older  genus.  Tropidonotus  has  a  vast  range 

*  Brown,  A.  E.      Variations  of  Eutaenia." 

t  Buthven  A.  G.    "Variations  of  the  Garter  Snakes." 


OEIGIN  OF  THE   GARTER   SNAKES  129 

from  north  Australia  through  the  Malay  Archipelago  and 
northward  to  Japan.  Westward  it  extends  to  India,  Africa 
and  Europe.  In  America  the  genus  occurs  principally 
in  the  eastern  States,  but  there  is  also  a  species  in  Cuba 
and  several  in  Central  America.  None  have  penetrated 
to  South  America.  From  Dr.  Boulenger's  *  catalogue  and 
Dr.  Stejneger's  description  of  Japanese  forms,f  it  seems 
evident  that  the  east  Asiatic  forms  are  not  very  closely 
related  to  the  American  ones.  On  the  other  hand,  Tro- 
pidonotus  validus,  from  Lower  California,  Arizona  and 
Mexico,  is  nearly  akin  to  the  west  European  Tropidonotus 
viperinus,  whose  high  antiquity  is  indicated  by  its  occur- 
rence in  Sardinia  and  Algeria.  I  may  have  another  oppor- 
tunity later  on  of  dealing  with  this  interesting  genus,  but 
it  must  be  conceded  that  although  we  possess  no  fossil 
evidence,  the  origin  of  Tropidonotus  must  date  back  at  least 
to  the  commencement  of  the  Tertiary  Era.  In  another  chapter 
I  shall  show  how  extraordinarily  intimate  is  the  relationship 
of  the  south-west  American  and  the  West  European  faunas. 
Evidence  will  then  be  given  in  support  of  the  theory  that 
southern  Europe  and  the  south-western  parts  of  North 
America  have  been  connected  with  one  another  by  land,  and 
that  we  probably  owe  the  resemblance  in  the  animals  and 
plants  of  these  two  regions  to  that  fact.  The  species  of 
Tropidonotus,  in  America  at  any  rate,  are  semi)- aquatic.  They 
are  so  much  attached  to  water  that  they  are  popularly  known 
as  "  water-snakes,"  whereas  the  garter-snakes  are  much  less 
bound  to  the  neighbourhood  of  water.  The  latter  are  not 
uncommonly  found  on  higher  ground  and  in  drier  situations, 
a  change  in  the  climatic  conditions  of  the  south-west  may  thus 
originally  have  given  rise  to  the  Thamnophis  branch  from  the 
original  Tropidonotus  stock.  The  headquarters  of  Tropi- 
donotus now  lie  in  the  eastern  States,  where  the  conditions 
for  its  existence  are  more  favourable  than  in  the  south-west. 
All  the  same,  it  seems  probable  that  the  original  centre  of  dis- 
persal was  in  the  south-west,  for  when  Tropidonotus  arrived 

*  Boulenger,  GK  A.,  "  Catalogue  of  the  Snakes  in  the  British  Museum,', 
Vol  1. 

t  Stejneger,  L.,   "  Herpetology  of  Japan,"  pp.  264 — 294. 

L.A.  K 


130  ORIGIN  OF  LIFE  IN   AMERICA 

in  North  America  the  climate  of  that  region  must  have  been 
very  different  from  what  it  is  at  present. 

I  may  just  mention  two  other  examples  of  innocuous  snakes 
which  frequent  the  north-eastern  States,  viz.,  the  smooth 
green  snake  (Liopeltis  vernalis),  and  the  rough  green  snake 
(Cyclophis  aestivus).  The  former  is  abundant  in  New  York 
State  and  northward  as  far  as  south-eastern  Canada.  South- 
ward it  ranges  to  the  Gulf  of  Mexico  and  westward  to  New 
Mexico,  becoming  rarer  as  we  approach  the  drier  and  warmer 
districts.  The  other  does  not  extend  nearly  so  far  north.  On 
the  other  hand,  the  rough  green  snake  is  found  westward  as 
far  as  northern  Mexico  and  California.  Both  of  them  share 
the  peculiarity  of  being  the  only  members  known  in  America 
of  the  genera  to  which  they  belong.  That  is  not  the  only  fea- 
ture of  interest  about  their  distribution.  I  have  just  urged 
that  the  ancestors  of  the  American  species  of  Tropidonotus 
must  have  come  from  Europe.  We  cannot  claim  the  same 
origin  for  the  American  species  of  Liopeltis  and  Cyclophis, 
for  neither  of  these  genera  inhabits  Europe.  Both  of  them  are 
absent  also  from  Africa.  Their  headquarters  are  in  southern 
and  eastern  Asia,  but  they  do  not  extend  as  far  north  as  Japan. 
Formerly  these  snakes  were  classed  among  that  insoluble 
zoogeographical  enigma,  namely,  the  group  of  animals  and 
plants  peculiar  to  eastern  Asia  and  eastern  America.  Now 
we  have  advanced  in  so  far  as  we  have  been  able  to  trace 
some  of  the  eastern  forms  to  an  originally  western  American 
range.  It  has  been  made  easier,  therefore,  for  those  natura- 
lists who  are  in  the  habit  of  explaining  anomalies  of  dis- 
tribution by  the  convenient  flotsam -jetsam  theory,  to  bring 
their  views  to  bear  upon  problems  such  as  those  suggested 
by  the  two  green  snakes.  That  these  snakes  could  have  been 
floated  across  the  Pacific  Ocean  on  a  raft  by  any  possible 
chance,  is  to  me  inconceivable.  That  they  should  have  utilised 
the  Bering  Strait  land  connection,  and  subsequently  have 
become  extinct  all  along  north-eastern  Asia  and  north-western 
North  America  does  not  appeal  to  me  either  as  likely.  We 
must  only  leave  the  consideration  of  the  problem  for  the  pre- 
sent, as  was  done  in  the  case  of  the  lizard  genera  Eumeces 
and  Lygosoma,  which  also  apparently  had  an  east  Asiatic 
origin. 


RANGE   OF  RATTLESNAKES  131 

From  the  popular  point  of  view,  as  Dr.  Ditmars  *  remarks, 
the  venomous  rattlesnakes  are  the  most  interesting  of  the 
American  serpents.  The  Old  World  naturalist  involuntarily 
associates  America  with  rattlesnakes  ;  and  the  ominous  warn- 
ing sound  produced  by  the  unique  appendage  at  their  tail 
alone  exercises  a  strange  fascination  on  everyone  who  has 
become  acquainted  with  them.  Not  only  is  the  common  rattle- 
snake (Crotalus  horridus)  abundant  in  some  of  the  hilly  por- 
tions of  New  York  and  Massachusetts,  it  actually  appears  to 
be  increasing  in  numbers  in  these  populous  States,  owing  to 
the  decrease  of  its  natural  enemies.  From  a  zoogeographical 
point  of  view  rattlesnakes  are  of  considerable  importance, 
because,  being  strictly  limited  to  the  ground,  they  are  less 
liable  to  accidental  dispersal  than  the  members  of  many 
other  genera  which  are  expert  swimmers  or  fond  of  climbing 
trees.  The  rattlesnakes  are  generally  divided  into  two  genera, 
viz.,  the  pigmy  rattlesnakes  (Sistrurus)  and  the  rattlesnakes 
proper  (Crotalus).  Both  genera  range  almost  all  over  the 
United  States,  a  couple  of  species  even  cross  the  borders 
of  Canada.  Southward,  Sistrurus  is  also  met  with  in  Mexico. 
The  true  rattlesnakes  (Crotalus),  on  the  other  hand,  have  a 
much  wider  distribution  in  America,  one  species  (C.  terrificus) 
having  been  found  in  Mexico  as  well  as  'in  Yucatan,  Bolivia, 
Venezuela,  northern  Argentina,  and  southern  Brazil. 

Remains  of  rattlesnakes  have  been  noticed  in  a  couple  of  the 
North  American  caves,  otherwise  they  are  unknown  in  earlier 
deposits.  Their  range  is  confined  to  America,  and  we  have 
no  reason  to  suppose  that  they  have  originated  in  any  other 
continent.  Their  home  is,  no  doubt,  as  Dr.  Brown  f  suggests, 
in  the  south-western  States  in  what  he  calls  the  Chihuahuan 
district.  We  have  no  means  of  estimating  the  age  of  the  two 
genera  of  rattlesnakes.  Yet  Crotalus  seems  to  be  the  more 
ancient,  and,  like  its  near  relation  Lachesis  of  southern  Asia, 
Central  and  South  America,  has  probably  a  remote  ancestry. 
It  may  possibly  have  inhabited  North  America  since  early 
Tertiary  times. 

I  have  drawn  particular  attention  to  the  fact  that  the 

*  Ditmars,  E.  L.,  "  The  Eeptile  Book,"  p.  426. 

t  Brown,  A.  E.,  "  Texas  Eeptiles  and  their  Faunal  Eolations,"  p.  558. 

K2 


132  OKIGIN   OF   LIFE   IN   AMEEICA 

great  scarcity  of  lizards  and  the  abundance  of  snakes  are 
characteristic  features  of  the  north-eastern  States  of  North 
America.  But  I  have  not  yet  alluded  to  the  most  remarkable 
feature  of  the  reptilian  fauna  of  that  region,  as  it  is  not  a 
character  readily  noticeable  to  the  untrained  naturalist.  It 
is  the  great  wealth  of  land  and  fresh-water  tortoises.  In 
England  it  is  customary  to  distinguish  the  marine,  paddle- 
limbed  kinds  of  Chelonians  as  "  turtles,"  all  others  as  "  land 
and  water  tortoises."  In  America  the  term  "  turtle  "  is 
usually  employed  quite  indiscriminately  to  true  tortoises  and 
turtles.  In  adopting  the  common  American  names  applied 
to  these  tortoises,  I  am  only  endeavouring  to  make  my 
remarks  quite  clear  to  American  readers. 

I  have  had  occasion  already  to  refer  to  one  species  of 
fresh-water  tortoise  (p.  51),  sometimes  called  "  semi  -box  " 
turtle  (Emys  blandingi),  and  to  discuss  the  peculiar  range 
of  the  genus,  which  is  confined  to  parts  of  Canada  and  the 
northern  States  in  America,  and  to  central  and  southern 
Europe  in  the  Old  World.  We  possess  no  fossil  remains  pf 
any  members  of  the  genus  except  from  recent  geological 
deposits.  Although  we  must  assume  that  a  migration  has 
taken  place  either  from  North  America  to  Europe,  or  vice 
versa,  in  more  remote  times,  palaeontology  gives  us  no  clue 
as  to  the  origin  of  Emys.  We  can  only  surmise  that  the 
genus  and  species  of  Emys  are  ancient  from  the  fact  that 
the  genus  Clemmys  occurs  in  the  Eocene  of  North  America, 
while  Chrysemys  has  been  discovered  in  the  Eocene  of 
Europe.  Both  of  these  are  still  living  genera  of  turtles  and 
closely  allied  to  Emys.  They  are  classed  among  what  are 
called  "  terrapins  "  in  North  America. 

The  terrapins  are  characterised  by  their  broad,  flattened 
shell.  The  hind  feet  are  extensively  webbed,  and  they  are 
good  swimmers.  Perhaps  the  best  known  of  the  terrapins 
is  the  "diamond-back"  (Malacoclemmys*  centrata)*  which 
frequents  the  salt  marshes  of  the  Atlantic  coast.  It  is  in 
great  favour  in  the  States  as  an  article  of  diet.  The  less, 
familiar  spotted  turtle  (Clemmys  guttata)  is  of  greater  zoo- 

*  Ditmars,  E.  L.,  "The  Eeptile  Book."  Siebenrock,  F.,  "Synopsis 
der  Schildkroten." 


AMEEICAN   TURTLES  133 

geographical  interest.  Four  species  Oiccur  in  North  America, 
three  of  them  being  limited  in  distribution  to  the  eastern 
States.  Only  one,  viz. :  Clemmys  marmorata,  is  quite  con- 
fined to  the  rivers  and  ponds  west  of  the  Cascade  and  Sierra 
Nevada  Mountains  in  Oregon  and  California.  In  Central 
and  South  America  the  genus  is  unknown,  but  in  eastern 
Asia  we  find  four  species.  One  of  them  inhabits  Japan, 
another  the  island  of  Hainan,  and  a  couple  of  them  China. 
Far  away  in  western  Asia  we  meet  with  another  species  in 
Persia  and  Mesopotamia,  spreading  across  Asia  Minor  to 
Greece  and  Turkey,  while  finally  Clemmys  leprosa  lives  in 
Spain,  Portugal  and  north  and  western  Africa  as  far  as  Sene- 
gambia.  The  genus  is  thus  quite  confined  to  the  northern 
hemisphere.  We  might  suppose  that  the  ancestor  of  the 
American  Clemmys  insculpta  had  spread  northward  from 
eastern  Asia  in  Pliocene  times  and,  after  crossing  the  Bering 
Strait  land  bridge,  had  invaded  Alaska  and  Canada,  ulti- 
mately reaching  the  eastern  States  of  America  in  that 
manner,  and  subsequently  becoming  extinct  in  the  vast  tract 
of  country  which  now  separates  the  Chinese  from  the  eastern 
American  species.  The  south-western  Clemmys  marmorata 
would  thus  have  been  the  latest  development  of  the  genus 
in  America.  Such  a  supposition  seems  unlikely,  owing 
to  the  unsuitability  of  the  western  States  for  such, 
turtles.  The  few  that  now  inhabit  the  west  are  rather  to  be 
regarded  as  ancient  survivals  of  a  long-distant  age  when 
the  climatic  conditions  were  much  more  favourable  for  them 
than  at  present.  The  earliest  member  of  the  genus  indeed 
(C.  morrisiae),  is  found  in  a  western  Eocene  deposit  (Bridger 
beds),  and  Dr.  Hay*  expresses  the  opinion  that  North 
America  is  probably  the  original  home  of  Clemmys.  If  so, 
the  genus  could  not  possibly  have  spread  to  Asia,  and  thence 
to  western  Europe  in  Pliocene  times.  The  existing  centres 
of  distribution  must  have  become  established  during  much 
more  remote  geological  periods.  Anyhow,  although  the 
majority  of  the  American  species  of  Clemmys  are  now  con  - 
fined  to  the  east,  we  have  ample  palaeontological  evidence 
of  its  having  formerly  lived  in  the  west. 

*  Hay,  O.  P.,  "  Fossil  Turtles  of  North  America,"  p.  290, 


134  ORIGIN   OF   LIFE   IN   AMERICA 

Besides  these  so-called  fresh-water  turtles,  we  have  in 
America  even  terrestrial  ones.  The  box-turtles  (Terrapene 
=  Cistudo),  for  instance,  are  strictly  confined  to  the  land,  where 
they  live  largely  on  vegetable  matter  and  berries.  The  six 
species  are  distributed  from  Mexico  in  the  south-west  to  the 
New  England  States  in  the  north-east.  In  the  more  northern 
habitats  they  burrow  to  some  depth  in  soft  ground  and  pass 
the  winter  there.  All  the  box  turtles  inhabit  North  America, 
the  genus  Terrapene  to  which  they  belong  being,  in  Dr.  Hay's 
opinion,  of  North  American  origin.  The  oldest  fossil  species 
(T.  putnami)  comes  from  a  deposit  in  Florida  stated  to  be 
of  Pliocene  age.  Dr.  Hay  *  is  inclined  to  the  belief  that  the 
genus  arose  in  North  America,  having  probably  been  derived 
from  Emys.  If  this  should  be  the  case,  the  origin  of  Emys 
itself  must  have  taken  place  at  a  much  earlier  date  than  the 
Pliocene.  Indeed  it  is  possible  that  Emys  is  one  of  the  most 
ancient  of  Chelonian  genera,  for  Dr.  Boulenger  f  argued  that 
it  is  in  many  respects  the  least  specialized  of  the  Emydidae 
and  that  it  should  be  placed  at  the  base  of  the  family.  It  is 
of  interest  to  note  that  although  box  turtles  lived  in  North 
America  at  least  since  Pliocene  times,  they  have  not  been 
able  to  spread  beyond  the  confines  of  the  continent.  This 
gives  us  some  idea  of  the  slow  rate  of  dispersal  of  these 
creatures. 

Of  the  family  of  snapping  turtles  (Chelydridae)  a  few 
fossil  remains  are  known  from  the  Jurassic  and  Cretaceous, 
though  not  of  existing  genera.  To  judge  from  their  distri- 
bution the  latter  must  nevertheless  be  very  ancient.  These 
large  fresh-water  Chelonians  with  their  proportionately  huge 
and  sinisters  heads,  are,  according  to  Dr.  Ditmars,  bold  and 
aggressive  fighters,  their  massive,  keen-edged  jaws  causing 
them  to  be  the  terror  of  most  of  the  aquatic  and  semi -aquatic 
creatures.  There  are  three  species  in  North  America.  One 
of  these  ranges  from  Mexico,  east  of  the  Bocky  Mountains, 
to  Canada,  but  far  to  the  south  of  Mexico  the  same  species 
(Chelydra  serpentina)  reappears  in  Ecuador.  Such  a  very 
peculiar  discontinuous  range  is  not  unknown  among  fresh- 

*  Hay,  0.  P.,  "Fossil  Turtles  of  North  America,"  p.  360. 
f  Boulenger  G.  A.,  "  Catalogue  of  Chelonia,"  p.  49, 


GIANT   SALAMANDEKS  135 

water  animals,  as  we  shall  learn  later  on.  A  second  species 
(Chelydra  rossignonii)  is  confined  to  Mexico  and  Guatemala. 
The  so-called  alligator  snapping-turtle  (Macros!  emmys  tem- 
minckii),  which  belongs  to  another  genus,  frequents  the 
rivers  emptying  into  the  Gulf  of  Mexico,  being  common  in  the 
Mississippi  as  far  north  as  Missouri.  Now  the  most  striking 
zoogeographical  feature  of  the  family  Chelydridae  is,  that 
right  across  the  Pacific  Ocean  we  meet  with  another  snapping 
turtle  (Devisia  mythodes)  in  the  Fly  River  of  New  Guinea, 
the  same  river  that  contains  the  unique  members  of  the  family 
Carettochelyidae.  In  many  other  respects  New  Guinea  has 
acquired  the  reputation  of  being  the  home  of  remarkable  and 
peculiar  types  of  animals,  and  no  doubt  the  island  .once 
formed  part  of  an  ancient  land,  most  of  which  has  long  since 
been  submerged. 

Quite  as  instructive  and  important  from  a  distributional 
point  of  view  as  the  reptiles  are  the  amphibians.  We  can 
roughly  divide  the  latter  into  tailed  amphibians,  such  as  the 
newt  and  salamander,  and  tailless  ones,  of  which  the  frog 
and  toad  are  examples.  All  these  are  amply  represented  in 
the  north-eastern  States  of  North  America,  and  we  notice 
among  them  that  same  curious  relationship  between  eastern 
America  and  eastern  Asia  which  has  given  rise  to  so  much 
comment  among  naturalists. 

Two  kinds  of  giant  salamanders  are  known  to  exist  in  the 
world.  One  of  these,  the  so-called  "hellbender"  (Crypto - 
branchus  allegheniensis),  lives  in  the  eastern  States  of  North 
America,  the  other,  (Cryptobranchus  or  Megalobatrachus 
japonicus),  in  the  mountain  streams  of  Japan.  The  hell- 
bender is  a  voracious  lead-coloured  slimy  creature,  living 
in  the  Allegheny  and  other  eastern  rivers,  where  it  feeds  on 
worms  and  fish.  It  grows  to  a  length  of  two  feet,  while 
its  Asiatic  relative  attains  to  double  that  size.  Of  the  geo- 
logical history  of  the  giant  salamanders  we  know  nothing 
as  far  as  America  and  Asia  are  concerned,  but  in  the  Miocene 
of  Switzerland  a  large  amphibian  was  discovered,  which 
appears  to  be  closely  allied,  though  now  referred  to  the 
distinct  genus  Proteocordylus.  To  suppose  that  these  relicts 
of  bygone  ages  are  no  older  than  Miocene  would  scarcely  be 
justified.  In  the  absence  of  palaeontological  evidence,  we  must 


136  ORIGIN   OF   LIFE   IN   AMERICA 

depend  upon  the  testimony  based  on  the  remarkably  discon- 
tinuous ranges  of  the  two  recent  species.  Any  theory  as  to 
the  home  of  the  giant  salamanders  should  be  founded  on  that 
of  other  animals  possessing  a  similar  range. 

The  hellbender  is  not  the  only  large  amphibian  frequent- 
ing tihe  rivers  of  the  eastern  States.  A  somewhat  eel -like 
creature,  with  feeble  diminutive  limbs  and  three  pairs  of 
bushy  external  gills,  inhabits  many  of  the  larger  streams 
and  lakes  in  the  north-eastern  States.*  It  grows  to  about  the 
same  length  as  the  giant  salamander,  but  belongs  to  quite  a 
different  family.  It  is  commonly  known  as  the  "  Mud  puppy  " 
(Necturus  maculatus),  and  does  not  occur  west  of  the  Rocky 
Mountains.  Now  in  this  case  the  nearest  relation  of  the  east 
American  form  does  not  live  in  Eastern  Asia,  but,  like  that 
of  the  mud  minnow  (see  p.  51),  in  Eastern  Europe.  This 
European  member  of  the  family  Proteidae  has  manifestly 
undergone  a  certain  amount  of  degeneration.  It  possesses 
only  three  fingers  and  two  toes,  is  completely  blind,  and  is 
restricted  to  the  subterranean  waters  of  Dalmatia  and  the 
neighbouring  provinces  of  southern  Austria.  The  ''Olm" 
(Proteus  anguineus),  as  it  is  called,  is  scarcely  a  foot  long, 
and  quite  white  except  for  the  gill  bunches  which  are 
brilliantly  red  in  colour.  It  was  believed  that  the  Texas 
subterranean  newt  (Typhlomolge  rathbuni)  was  related  to 
the  mud  puppy.  Miss  Emerson,f  however,  has  shown  that 
it  is  a  salamandrid.  No  fossil  remains  of  any  of  these  amphi- 
bians are  known,  and  any  theories  as  to  the  origin  of  the 
discontinuous  distribution  of  the  members  of  this  ancient 
family,  must  be  based  on  zoogeographical  data. 

The  family  of  true  salamanders  and  newts  (Salamandridae) 
likewise  comprises  certain  members  which  seem  to  be  of 
very  ancient  origin,  such  as  the  blunt-nosed  salamanders 
(Amblystoma).  Being  only  semi-aquatic  animals,  they 
possess  greater  facilities  for  dispersal  than  the  purely  fresh- 
water forms.  Most  of  them  are  large  species,  the  tiger  sala- 
mander (Amblystoma  tigrinum)  growing  to  nearly  a  foot  in 
length,  and  they  only  repair  to  the  water  in  the  spring  to 

*  Cope,  E.  D.,  "  Batrachia  of  North  America,"  p.  26. 
+  Emerson,  E.  T.,  "Anatomy  of  Typhlomolge,"  p.  72. 


NEWTS   AND    SALAMANDERS  137 

deposit  their  eggs.  The  tiger  salamander  is  variable  in 
colour.  Generally  of  a  dark  brown,  it  is  marked  with 
irregular  yellow  blotches,  and  is  commonly  met  with  under 
stones  and  in  decayed  hollow  trees.  At  the  time  when  the 
Spanish  conquerors  landed  in  Mexico,  the  natives  were  in 
the  habit  of  eating  roasted  or  boiled  fresh-water  creatures, 
which  they  called  "  axolotls."  It  is  now  known  that  these 
axolotls  are  nothing  but  the  larval  forms  of  the  tiger  sala- 
mander, which  is  found  from  Mexico  to  the  city  of  New  York. 
Under  certain  conditions,  the  larva,  instead  of  losing  its  gills 
and  turning  into  the  terrestrial  salamander,  retains  them, 
and  continues  its  existence  in  the  medium  in  which  it  was 
born,  growing  into  a  creature  somewhat  resembling  the  hell- 
bender, and  breeding  without  leaving  the  water. 

The  genus  Amblystoma  is  almost  confined  to  Mexico,  the 
United  States  and  Canada.  Only  one  species  (A.  persimile), 
which  most  resembles  Amblystoma  jeffersonianum  of  the  eastern 
States  and  Canada,  inhabits  the  far  distant  mountains  of  Siam 
and  Upper  Burmah.  This  represents,  therefore,  another 
example  of  that  curious  relationship  between  eastern  North 
America  and  Asia.  In  this  case,  however,  it  is  with  southern 
instead  of  eastern  Asia,  while  the  genus  in  North  America  occurs 
in  the  south-west  as  well  as  in  the  eastern  States. 

Several  smaller  kinds  of  newts  have  been  observed  in 
the  eastern  States.  Among  them  there  are  several  belong- 
ing to  the  genus  Spelerpes,  which  are  worthy  of  special  com- 
ment. They  all  display  remarkably  brilliant  colours,  and 
these  make  them  more  attractive  than  salamanders  usually 
are.  Quite  apart  from  this  feature,  their  method  of  feeding 
is  interesting  to  watch.  Like  chameleons,  they  possess  an 
enormously  long  tongue,  ending  in  a  soft  sticky  knob,  which 
is  shot  out  of  the  mouth  with  extreme  rapidity  at  any  insect 
coming  within  range  and  likely  to  he  a  dainty  morsel.  About 
twenty  species  of  Spelerpes  are  known  to  science,  the  head- 
quarters of  the  genus  being  in  Mexico.  Dr.  Gadow*  dis- 
covered several  of  them  at  considerable  heights.  Spelerpes 
orizahensis  and  S.  leprosus  ascend  to  12,000  feet,  and  S. 
chiropterus  to  10,000  feet,  above  sea-level. 

*  Gadow,  H.,  "  Mexican  Amphibians  and  Eeptiles,"  p.  203. 


138  ORIGIN    OF   LIFE   IN   AMERICA 

Their  earliest  centre  of  distribution  lay  in  what  has  been 
called  Sonoraland,  or  south-western  North  America,  and 
from  here  the  species  have  spread  in  Miocene  times,  according 
to  Dr.  Gadow,  to  the  eastern  States,  to  the  island  of  Haiti 
and  even  to  Peru.  The  latter  occurrence  is  of  particular 
importance,  as  we  shall  see  later  on,  when  we  come  to  the 
consideration  of  the  points  of  resemblance  between  the 
Mexican  and  the  South  American  faunas.  Still  more  remark- 
able is  the  fact  that  a  single  species  of  Spelerpes  (S.  fuscus)  is 
known  from  some  of  the  remaining  fragments  of  the  ancient 
Tyrrhenian  continent  in  southern  Europe  (see  Fig.  8).  Even 
Dr.  Gadow,*  who  shows  little  inclination  for  reconstructing 
ancient  land  bridges,  does  not  suggest  that  this  salamander 
could  have  crossed  the  Atlantic  Ocean  without  their 
assistance.  He  thinks  a  land  connection  joining  north- 
eastern North  America  with  north-western  Europe,  by  way 
of  Greenland,  might  have  enabled  the  south  European 
Spelerpes  to  cross  from  the  New  World  to  the  Old. 
I  concur  with  Dr.  Gadow  in  the  belief  of  the  former 
existence  of  a  land  bridge  in  the  extreme  North  Atlantic, 
but  I  am  of  the  opinion  that  it  had  not  yet  made  its  appear- 
ance at  the  time  when  Spelerpes  undertook  its  journey  to 
Europe. 

This  short  review  of  some  of  the  characteristic  north- 
eastern reptiles  and  amphibians  has  clearly  revealed  a 
relationship  of  some  of  the  older  forms  with  those  of  southern 
and  eastern  Asia  and  also  of  southern  Europe.  In  several 
instances  it  was  demonstrated  that  the  eastern  States  were 
not  the  original  home  of  the  genera,  but  that  the  North 
American  centre  of  distribution  lay  in  the  south-west.  Hence 
it  seems  possible  that  the  south-west  was  in  remote  times,  say 
about  the  commencement  of  the  Tertiary  Era,  the  great  centre 
from  which  reptiles  and  amphibians  wandered  eastward. 
Owing  to  subsequent  changes  in  the  climatic  conditions  of 
the  south-west,  some  genera,  and  even  families,  probably 
became  extinct  there,  thus  obscuring  the  original  relation- 
ship of  that  part  of  North  America  with  Asia  and  Europe. 
Without  fossil  evidence  to  guide  us,  it  would  seem  as  if  these 

*  Gadow,  H.,  "  Mexican  Amphibians  and  Keptiies,"  p.  244, 


AFFINITIES   OF   EASTERN   PLANTS  139 

speculations  were  based  on  somewhat  unreliable  foundation. 
We  may  therefore  call  to  our  aid  another  branch  of  the  geo- 
graphical distribution  of  living  organisms,  namely  that  of 
plants,  so  as  to  test  the  validity  of  these  theories. 

Professor  Asa  Gray  *  was  the  first  to  direct  attention,  in 
1859,  to  the  striking  similarity  of  the  flora  of  eastern  Asia 
to  that  of  the  eastern  States  of  North  America.  In  a  popular 
raccount  of  the  distribution  of  the  North  American  flora,  Sir 
Joseph  Hooker  again  alluded  to  this  feature  more  recently, 
stating  that  there  is  actually  specific  identity  in  about  two 
hundred  and  thirty  cases,  and  very  close  representation  in 
upward  of  three  hundred  and  fifty.  What  is  most  curious,  he 
says,  is  that  there  are  not  a  few  very  singular  genera  of  which 
only  two  species  are  known,  one*  in  east  Asia,  the  other  in 
east  America.  In  some  of  these  instances  the  Asiatic  species 
is  a  widespread  plant  in  east  Asia,  whilst  the  American  is  an 
extremely  scarce  and  local  plant.  This  and  other  conditions 
render  it  conceivable,  according  to  Sir  Joseph  Hooker,f  that 
the  Asiatic  element  in  east  America  is  dying  out. 

Still  more  recently  Professor  Engler  discussed  the  same 
subject  very  fully.  He  believes  that  the  number  of  species 
common  to  the  eastern  States  and  eastern  Asia  is  far  less 
than  Sir  Joseph  Hooker  thought.  Some  of  these  occur  also 
in  the  north,  others  in  western  North  America.  Yet  there 
are  certain  plants  which  exhibit  extraordinarily  discontinu- 
ous distribution,  quite  comparable  to  what  we  have  noticed 
among  reptiles.  Monotropa  uniflora  and  Phryma  lepto- 
stachya,  for  instance,  occur  only  in  the  eastern  States,  in 
Japan  and  the  Himalayan  Mountains.  Professor  Engler 
looks  upon  these  as  relicts  of  a  flora  which  was  uniformly  dis- 
tributed in  Tertiary  times  between  the  Himalayan  Mountains 
and  North  America.  Of  the  genera  Liquidambar,  Ostrya, 
Platanus,  and  Castanea,  we  know  that  they  lived  further  north 
in  Tertiary  times  than  they  do  now.  We  have  also  learned 
from  the  Pliocene  and  Miocene  beds  of  the  Eocky  Mountains, 
as  Professor  Engler  points  out,  that  the  flora  west  of  these 
mountains  was  formerly  not  so  distinct  from  that  of  the 

*  Gray,  A.,  "Eelations  of  Japanese  Flora." 

t  Hooker,  J,  D.,  "North  American  Flora,"  p.  573, 


140  ORIGIN   OF   LIFE   IN   AMERICA 

eastern  States  as  it  is  at  present.  A  more  pronounced 
climatic  differentiation  between  the  two  parts  of  North 
America  supervened,  he  thinks,  in  later  Tertiary  times,  and 
while  many  of  the  species  became  extinct  in  the  western 
States  owing  to  the  gradually  increasing  dryness  of  the 
climate,  new  forms  better  adapted  to  the  altered  conditions 
arose.  Hence  certain  types  of  plants  are  represented  in  the 
western  States  by  many,  and  in  the  eastern  by  few  species. 

It  is  evident  that  Professor  Engler*  favours  the  view  that 
the  western  States  were  once  much  more  nearly  related  in 
their  flora  to  eastern  and  southern  Asia  than  the  eastern 
States,  and  that  the  present  similarity  between  the  latter 
regions  has  arisen  as  a  secondary  character.  Professor 
Engler,  moreover,  believes — and  in  this  respect  my  views 
differ  from  his — that  Japan,  western  and  eastern  America 
were  connected  with  one  another  in  the  north  during  the 
Tertiary  Era  and  probably  even  in  Cretaceous  times,  forming 
three  great  peninsulas  of  land  joined  at  their  northern  bases. 
At  any  rate,  the  distribution  of  plants  in  America  seems  to 
offer  a  certain  amount  of  support  to  the  view  suggested,  that 
the  relationship  of  the  east  American  and  east  Asiatic  faunas 
is  due  to  the  recent  geological  changes  in  south-western  North 
America  having  obliterated  the  more  striking  features  of 
resemblance  between  the  latter  and  eastern  Asia. 

In  connection  with  the  character  of  the  north  eastern  flora 
just  referred  to,  I  might  offer  a  few  remarks  on  the  subject 
of  the  supposed  former  eastward  extension  of  the  land.  This 
subject  was  discussed  towards  the  end  of  the  second  chapter. 
I  then  maintained  that,  although  the  north-eastern  States 
had  been  under  water  in  Pleistocene  times,  unsubmerged 
land  existed  to  the  eastward  quite  close  to,  and  including 
portions  of  the  present  shore-line. 

Probably  one  of  the  best  recognised  and  most  characteristic 
elements  of  the  eastern  North  American  floras,  as  Mr.  Hollick 
remarks,  is  the  one  generally  known  as  the  "  Pine-barren 
flora,"  which  is  such  a  prominent  feature  throughout  the 
eastern  and  southern  parts  of  New  Jersey  and  southward. 

*  Engler,  A.,  "  Entwicklungsgeschichte  d.  Florengebiete,"  I.,  pp.  22 — 
37. 


PINE -BARKEN   FLORA  141 

Now  this  flora  has  a  curiously  discontinuous  range  further 
north-eastward.  It  disappears  from  the  mainland  almost 
entirely,  but  reappears  on  Staten  Island  and  Long  Island. 
Still  further  east  comes  a  stretch,  of  eighty  miles  of  sea, 
beyond  which  the  pine -barren  flora  once  more  is  in  evidence 
on  Martha's  Vineyard  and  Nantucket  Islands.  On  a  limited 
stretch  of  the  opposite  mainland,  near  New  Bedford,  the  same 
flora  again  makes  its  appearance.  Further  north,  isolated 
members  of  the  flora  such  as  Magnolia  glauca,  from  near 
Cape  Ann,  are  known  from  certain  coastal  tracts. 

It  might  be  argued  that  this  discontinuous  distribution  is 
due  to  marine  currents  or  winds,  but  both  the  prevailing 
winds  and  the  currents  set  in  from  the  opposite  direction. 
It  would  not  explain  the  fact,  moreover,  that  the  pine-barren 
flora  is  almost  limited  to  the  islands.  Hence  it  seems  more 
likely  that  Long  Island  was  connected  by  land  with  Cape 
Cod,  forming  a  continuous  strip  of  land,  which  was  separated 
from  the  mainland  by  a  broad  river  or  a  lake,  as  Mr.  Hollick* 
suggests.  Mr.  Rollick's  theory  not  only  explains  the  method 
of  dispersal  of  the  southern  pine-barren  flora,  it  gives  us  a 
clue  to  the  problem  why  the  northern  Helix  hortensis,  which 
has  evidently  survived  as  a  relict  form,  should  be  almost 
confined  to  the  islands  off  the  coasts  of  Maine  and  Massa- 
chusetts. However,  while  I  believe  that  much  of  that  land 
which  lay  off  the  Atlantic  coast  remained  unaffected  by  the 
Glacial  deposits,  and  that  the  southern  flora  survived  the 
Glacial  Epoch  on  these  islands,  Mr.  Hollick  considers  the 
eastward  extension  of  Long  Island,  and  with  it  the  pine- 
barren  flora,  of  post-Glacial  age. 

I  have  mainly  dealt  with  reptiles  and  amphibians  in  this 
chapter,  because  they  form  a  very  characteristic  feature  of 
the  north-eastern  States.  Besides  no  opportunity  occurred 
of  mentioning  them  in  the  earlier  part  of  this  volume. 
The  mammals,  on  the  other  hand,  scarcely  need  further 
comment  here.  Only  comparatively  few  species  are  peculiar 
to  this  province.  Nevertheless,  there  is  an  order  which 
has  not  hitherto  been  alluded  to,  and  which  contains 
some  remarkable  form's  confined  to  the  eastern  States.  The 

*  Hollick,  A.,  "  Plant  Distribution,"  pp.  191—201. 


142  OKIGIN   OF   LIFE   IN   AMEEICA 

order  is  that  of  the  Insect! vora  or  insect-eaters.  They  are 
distinguished  externally  by  their  small  size  and  soft  dense 
fur,  while  many  of  them  are  adapted  for  an  underground  life 
and  possess  specially  modified  front  limbs  for  the  purpose 
of  digging. 

Five  different  genera  of  moles  (Talpidae)  are  known  from 
North  America,  and  three  of  these  are  restricted  in  distribu- 
tion to  the  eastern  States.  One  of  them,  containing  but  a 
single  species,  the  star-nosed  mole  (Condylura  cristata),  has 
its  headquarters  in  the  north-eastern  States,  extending  north- 
ward as  far  as  Hudson  Bay,  and  southward  to  North  Carolina 
(Fig.  9).  The  name  was  given  to  it  from  the  fact  that  a 
ring  of  riband-like  appendages  surrounds  the  end  of  the 
muzzle,  in  the  middle  of  which  are  situated  the  nostrils.  Like 
its  European  relative (Talpa  europaea),  it  constructs  extensive 
galleries  underground,  throwing  up  a  ridge  of  loose  earth 
along  the  line  of  the  tunnels.  No  fossil  remains  of  the  star- 
nosed  mole  having  ever  been  discovered,  palaeontology 
furnishes  no  evidence  as  to  its  past  history,  and  we  must 
assume  that  it  has  originated  in  north-eastern  North  America. 

What  is  often  known  as  the  common  mole  (Scalops 
aquaticus)  in  the  States,  is  no  near  relation  of  the  European 
species  of  that  description.  It  is  more  appropriately  called 
naked -tailed  mole.  The  Latin  name  aquaticus  was  given  to 
it  because  its  webbed  hind-feet  led  to  the  inference  that  it 
must  be  a  water  animal,  whereas  it  actually  lives  underground 
in  dry  sandy  soil.  Two  species  of  Scalops  are  known,  one  of 
them  occurs  from  Massachusetts  to  Florida,  the  other  further 
west,  in  the  Indian  Territory. 

Still  another  eastern  species  is  the  so-called  hairy-tailed 
mole  (Parascalops  breweri),  whose  habits  are  very  similar 
to  those  of  the  other  moles,  though  it  is  readily  distinguished 
from  them  by  its  thickly-haired  black  tail.  Its  range  extends 
along  the  Atlantic  coast,  from  New  Brunswick  in  the  north 
to  North  Carolina  in  the  south,  and  inland  to  the  shores  pf 
the  Great  Lakes.  It  is  even  said  to  occur  on  Martha's  Vine- 
yard Island  off  the  coast  of  Massachusetts,  which  locality  is 
of  interest  in  connection  with  the  view  expressed  above  as 
to  this  island  having  formed  part  of  an  ancient  land  surface 
now  partially  submerged. 


STAR-NOSED   MOLE  143 

As  for  the  geological  history  of  these  forms,  a  number  of 
insectivores  with  talpoid  dentition  have  been  met  with  in  the 
middle  Eocene  (Bridger)  of  North  America,  and  referred  to 
the  mole  family  (Talpidae),  but,  according  to  Dr.  Matthew, 
most  of  them  are  incompletely  known  and  of  doubtful 
affinities.*  The  first  undoubted  member  of  the  family  (Pro- 
scalops)  makes  its  appearance  in  the  Oligocene  beds  of 
Colorado,  being  apparently  related  to  the  modern  Scalops. 
Owing  to  their  subterranean  habits,  the  moles  are  rarely 
found  fossil,  except  in  fissures  such  as  those  of  La  Grive 
St.  Alban  in  southern  France.  Palaeontology  does  not  aid 
us  materially  in  solving  the  problem  as  to  the  place  of  origin 
of  the  Talpidae,  or  the  geological  period  during  which  the 
moles  have  wandered  from  one  continent  to  the  other.  We 
are  also  entirely  in  the  dark  as  to  the  route  they  have  taken 
on  entering  the  New  World  from  the  Old  or  vice  versa.  They 
may  possibly  have  spread  eastward  from  the  western  States, 
but  a  careful  comparative  study  of  the  living  American  moles  < 
seems  more  likely  to  elucidate  this  problem  than  palaeonto- 
logical  research. 

*  Matthew,  W.  D.,  "  Carnivora  and  Insectivora  of  the  Bridger,"  p.  536. 


CHAPTER  VII 

THE    CONTINENTAL    BASIN 

BOUNDED  in  the  east  by  what  might  collectively  be  termed 
the  Atlantic  Mountains  and  in  the  west  by  the  Pacific  Moun- 
tain .system  lies  the  immense  continental  basin.  It  is  open 
to  the  sea  both  in  the  north  and  south,  extending  in  one 
continuous  series  of  plains  and  plateaux  from  the  Gulf  of 
Mexico  to  the  Arctic  Ocean.  The  northern  portion  of  this 
great  interior  basin  has  already  been  briefly  described  in  the 
second  and  third  chapters.  The  rivers  of  this  part  of  the 
continent  drain  eastward  to  the  Atlantic  Ocean  and  northward 
to  Hudson  Bay  and  the  Arctic  Ocean.  The  drainage  of  the 
southern  portion  is  supplied  almost  entirely  by  the  Missis- 
sippi, and  is  thus  discharged  into  the  Gulf  of  Mexico.  It  is 
this  southern  section  of  North  America  and  its  fauna  with 
which  I  propose  to  deal  very  briefly  in  this  chapter. 

The  low-lying  and  gently  seaward-sloping  belt  of  land 
bordering  the  Gulf  of  Mexico  is  known  as  the  "  gulf  plains." 
It  is  here  in  this  rich  soil  that  sugar-cane,  cotton  and  rice  are 
cultivated.  The  west- central  part  of  the  continental  basin 
is  occupied  by  the  "  prairie  plains."  By  the  term  "  prairie  " 
we  recognise  a  level  region,  either  a  plain  or  a  plateau,  with- 
out forests,  but  clothed  in  a  carpet  of  luxuriant  grasses  and 
flowering  annuals.  On  their  eastern  and  northern  border 
these  prairie  plains  merge  into  the  adjacent  forested  plains, 
while  in  the  west  they  gradually  pass  into  the  more  elevated 
and  drier  high  plains,  where  bunch  grass,  with  bare  intervals 
between  the  scattered  tufts,  takes  the  place  of  the  continuous 
sod  of  the  true  prairies. 

There  is  a  widespread  popular  belief  in  Europe  that  the 
whole  of  the  vast  American  continental  basin  is  one  extensive 
prairie  or  pasture  land.  This  is  quite  a  mistake.  As  we 
approach  the  Mississippi  River  from  the  west  we  gradually 


THE   PKAIRIE   EEGION  145 

pass  from  the  treeless  prairie  to  the  forest  region,  which  is 
continued  eastward  as  far  as  the  Atlantic  Ocean.  In  the 
prairie  region  a  struggle  has  been  in  progress  for  thousands 
of  years  between  the  conditions  favouring  tree  growth  and 
those  adverse  to  them.  The  increase  in  the  mean  annual  pre- 
cipitation from  west  to  east  is  the  determinant  factor  in  forest 
production.  The  main  cause,  therefore,  of  the  absence  of  trees 
in  the  prairies  lies,  according  to  Professor  Kussell,*  in  the 
climatic  conditions,  and  principally  in  the  lack  of  sufficient 
rain  during  the  long,  hot  summers. 

A  thorough  survey  of  the  fauna  of  the  prairie  region  has 
still  to  be  made.  Dr.  Merriam  f  devotes  only  a  short  para- 
graph to  it.  Most  other  writers  have  confined  themselves  to, 
a  description  of  one  or  two  typical  prairie  forms.  The  sole 
attempt  to  give  us  a  more  lucid  impression  of  the  general 
'features  of  the  vertebrate  life  of  the  region  was  made  by 
Dr.  Kuthven.J  He  noticed  that  the  peculiar  conditions  of  the 
prairie  region  had  an  effect  on  the  fauna  in  modifying  the 
species  as  they  entered  this  region  from  the  adjoining  ones. 
Yet  he  thinks  that  there  is  a  great  difference  in  the  extent 
to.  which  the  species  of  eastern  North  America  push  westward,' 
or  the  plains-forms  eastward,  into  the  prairie  region,  before 
(becoming  modified  or  checked.  Dr.  Euthven's  studies  lead 
him  to  the  conclusion  that  the  prairie  region  is  an  extensive 
area  of  transition  between  the  plains  and  eastern  forest 
regions,  but  he  expresses  the  opinion  that  the  conditions  of 
environment  are  either  not  intensive  or  not  extensive  enough 
to  mould  the  animals  into  a  peculiar  fauna. 

What  was  once  the  most  characteristic  animal  of  the  prairie 
region  is  now  practically  extinct  in  the  United  States  in  its 
feral  condition.  I  need  no  longer  dwell  on  the  history  of  the 
extinction  of  the  bison,  the  animal  I  am  alluding  to,  for  it 
has  been  sufficiently  described  in  the  third  chapter  (pp. 
65 — 67).  When  discussing  the  question  of  the  bison's  origin, 
I  suggested  that  its  ancestors  might  have  invaded  North 


*  Kussell,  I.  0.,  "North  America,"  pp.  89—96. 
t  Merriam,  0.  H.,  "  Life  in  North  America,"  p.  20. 
I  Euthven,  A.  G.,  "Faunal  Affinities  of  Prairie  Eegion,"   pp.  390— 
393. 

L.A.  I* 


146  ORIGIN   OF    LIFE   IN    AMERICA 

America  from  Asia  in  pre-Glacial  times.     Long  before  the 
advent  of  the  European  conquerors  in  the  New  World,  herds 
of  another  large  ungulate,  the  horse,  roamed  about  these  same 
prairies  and  no  doubt  shared  the  abundant  fodder  with  the 
bison.    When  the  Spaniards  landed  in  America  in  1521  it  was 
already  extinct,  and  the  natives  had  not  any  knowledge  even  of 
the  former  existence  Of  the  horse  in  their  continent.    Yet  even 
in  Pleistocene  times  several  different  kinds  of  wild  horses 
still   lived   in   North   America   and  were  probably  contem- 
poraneous with  early  man.    One  of  these  (Equus  giganteus) 
seems  to  have  exceeded  in  size  any  known  race  of  horse  either 
living  or  extinct.*    What  caused  the  sudden  extinction  of  the 
wild  horse  all  over  America  we  do  not  know.      Professor 
Osbornf  suggests  that  a  disease  of  the  nature  of  the  African 
"  rinderpest  "  might  have  done  it.   The  "  tse-tse  fly  "  renders 
thousands  of  square  miles  of  Africa  uninhabitable  for  horses, 
and  the  invasion  of  a  similar  pest  into  America  might  pos- 
sibly have  swept  away  the  whole  of  the  equine  stock  in  a  short 
time.    But  the  interest  aroused  among  zoologists  by  the  dis- 
covery of  fossil  horses  in  America  was  not  only  connected  with 
their  unexplained  disappearance  in  modern  times,  it  yielded 
what  was  thought  to  be  absolutely  demonstrative  evidence  of 
the  theory  of  evolution.     Fossil  forms  no  doubt  had  already 
been  discovered  in  Europe  which  seemed  to  indicate  that 
the  remote  ancestors  of  the  existing  horse  had  five  digits  on 
every  foot  while  intermediate  stages  with  three  fully  deve- 
loped toes  were  known.     In  America,  horses,  or  at  any  rate 
animals  possessing  all  the  essential  characters  of  a  horse, 
have  been  brought  to  light  from  very  early  Tertiary  deposits, 
possessing  four  toes  and  a  rudimentary  fifth  on  the  hind  foot 
and  short-crowned  teeth.     These  are  succeeded  in  Oligocene 
and  Miocene  strata  by  others  with  three  toes  and  short- 
crowned  teeth.     In  still  more  recent  deposits,  horses  occur 
with   three    toes  and  long-crowned  teeth  which  are  finally 
followed  by  horses  of  the  modern  type  with  one  toe  and  long- 
crowned  teeth. 


*  Gidley,  J.  W.,  "  Ee vision  of  North  American  Species  of  Equus," 
p.  137. 

t  Osborn,  H.  F.,  "  Causes  of  Extinction  of  Mammalia,"  p.  835. 


GEOLOGICAL   HISTOKY   OF   HOKSE  147 

In  a  revision  of  the  American  Eocene  horses,  Mr.  Granger* 
distinguishes  twenty-six  species,  all  the  three  genera  to  which 
they  belong  being  distinct  from  the  early  horses  found  in 
Europe.  The  American  Eohippus  appears  to  be  closely  re- 
lated to  the  Old  World  Hyracotherium,  while  Epihippus  ap- 
proaches Lophiotherium.  We  thus  have  a  somewhat  parallel 
series  in  the  two  continents. 

In  the  Oligocene  deposits  the  horses  are  still  small,  some 
of  them  less  than  eighteen  inches  high  at  the  withers. 
Twenty-eight  species,  belonging  to  the  two  genera  Mesohippus 
and  Miohippus,  have  been  described  by  Professor  Osborn.f 
Sixty  more  species  are  mentioned  by  Mr.  GidleyJ  as  having 
been  procured  in  the  Miocene  and  Pliocene  beds,  and  over  half 
a  dozen  more  from  Pleistocene  strata.  Thus  we  know  from 
America  already  about  one  hundred  and  twenty  different  kinds 
of  fossil  horses.  They  gradually  increase  in  size  as  we  pro- 
ceed from  the  older  to  the  newer  deposits.  The  species  with 
many  toes  are  replaced  by  others  with  fewer  toes,  until  we 
come  to  the  highest  form  of  specialization  in  the  modern 
horse.  All  that  remains  of  the  outer  toes  is  a  splint-bone  left 
on  each:  side  of  the  single  toe,  while  the  teeth  which  originally 
possessed  short  crowns  have  now  long  ones.  There  is  ap- 
parently a  gradual  evolution  from  smaller  and  simpler  forms 
to  larger  and  more  complex  ones,  as  we  glance  from  the  older 
horse  remains  to  the  recent  ones.  And  yet  not  a  single  gradual  \ 
transition  from  one  genus  to  the  other  seems  to  be  known.  ; 
No  wonder  that  one  of  our  foremost  palaeontologists  exclaims : 
"  The  supposed  pedigree  of  the  horse  is  a  deceitful  delusion, 
which  simply  gives  us  the  general  process  by  which  the  tri- 
dactyle  foot  of  an  ungulate  can  be  transformed  in  various 
groups  into  a  monodactyl©  foot  in  view  of  an  adaptation  for 
speed,  but  this  in  no  way  enlightens  us  on  the  palaeontological 
origin  of  the  horse.  "§ 

Considering  the  extraordinary  abundance  of  horse  remains 
in  North  America,  and  even  in  the  south  of  South  America, 

*  Granger,  W.,  "  American  Eocene  Horses,"  p.  233. 
t  Osborn,  H.  F.,  "New  Oligocene  Horses." 

t  Gidley,  J.  W.,  "Miocene  and  Pliocene  Horses  of  North  America." 
§  Deperet,  C.  H.,  "  L' evolution  des  Mammiferes  Tertiaires,"  OXL., 
p.  1517. 

L2 


148  ORIGIN   OF   LIFE   IN   AMERICA 

it  would  seem  as  if  the  family  Equidae  had  originated  in 
America  and  had  sent  certain  offshoots  to  the  Old  World 
during  such  times  when  America  was  connected  by  land 
with  either  Asia  or  Europe.  Professor  Deperet  *  certainly 
takes  the  view  that  both  Anchitherium  and  Hipparion 
reached  Europe  by  means  of  a  land  connection  with  America, 
and  that  the  two  continents  were  several  times  joined  to  one 
another  by  land  during  the  Tertiary  Era.  This  opinion  is 
amply  supported  by  the  most  weighty  zoogeographical  evi- 
dence, as  will  be  shown  in  one  of  the  succeeding  chapters 
(pp.  226 — 231).  There  is,  indeed,  a  very  general  agreement 
among  palaeontologists  on  this  point.  The  only  difference  of 
opinion  concerns  the  exact  location  of  the  site  of  these  ancient 
land  bridges. 

One  of  the  most  characteristic  animals  of  the  great  plains 
is  the  so-called  "  prairie  dog  "  (Cynomys  ludovicianus) .  The 
name  has  been  applied  to  it  on  account  of  the  peculiar  barking 
sound  it  emits  when  alarmed.  Otherwise  it  has  nothing  to  do 
with  the  dog  family,  being  more  nearly  related  to  the  ground 
squirrels  and  marmots.  It  loves  the  sunshine  and  a  dry 
atmosphere,  and  becomes  less  and  less  numerous  as  we  ap- 
proach the  humid  prairies  from  the  west.  The  prairie  dog  is 
a  social  creature  living  in  colonies,  and  these,  according  to 
Dr.  Merriam,f  are  sometimes  from  twenty  to  thirty  miles  in 
length.  The  damage  done  to  crops  by  these  animals  is  enor- 
mous, while  their  increase  is  greatly  favoured  by  the  spread 
of  agriculture.  The  cultivation  of  the  soil  enables  them  to 
support  larger  families,  whereas  the  cultivator  further  pro- 
tects them  by  destroying  their  natural  enemies. 

The  prairie  dog  inhabits  a  vast  area  between  Montana  in 
the  north  and  southern  Texas  in  the  south.  Altogether  seven 
species  of  Cynomys  are  known,  some  of  which  range  into 
Arizona  and  Mexico,  whereas  none  occur  in  the  eastern  or 
extreme  western  States  of  America.  No  fossil  remains  of 
Cynomys  from  Tertiary  deposits  have  been  identified,  except 
from  the  Miocene  Republican  River  deposits  of  Kansas  and 
Nebraska,  and  even  they  only  doubtfully  belong  to  the  genus. 

*  Deperet,  Ch.,  "  Transformations  of  the  Animal  World,"  p.  313. 
t  Merriam,  C.  H.,  "Prairie  Dog,"  pp.  258—263. 


PEAIRIE   DOGS  149 

Cynomys,  however,  is  certainly  of  American  origin,  though 
some  of  its  near  relations,  as  I  have  shown,  have  probably  an 
Asiatic  ancestry. 

The  coyotes  or  prairie  wolves  have  been  described  as  the 
most  inveterate  enemies  of  the  prairie  dog.  They  are  small, 
graceful  creatures  hunting  in  packs  like  other  wolves,  but 
living  in  burrows  on  the  plains.  Not  long  ago  only  a  single 
kind  of  coyote  (Canis  latrans)  was  recognised.  More  than  a 
dozen  species  are  distinguished  now ;  some  of  them  on  rather 
slender  grounds.*  All  these  occur  west  of  the  Mississippi. 
The  presence  o'f  wolves  in  the  Arctic  regions  of  America  has 
been  alluded  to  (p.  11  and  p.  61),  but  I  have  not  hitherto 
made  any  remarks  on  their  past  history  and  origin. 

The  dog  tribe  (Canidae),  to  which  all  wolves  belong,  is 
more  widely  spread  in  the  world,  that  is  to  say,  it  has  a  larger 
geographical  distribution  than  any,  other  family  of  carnivores, 
one  species  being  even  found  wild  in  Australia.  Judging 
merely  from  the  extent  of  its  range,  the  family  Canidae  should 
be  a  very  ancient  one,  and  this  assumption  is  fully  borne  out 
by  the  knowledge  we  have  obtained  from  fossil  remains  of  the 
dog  tribe. 

According  to  one  of  the  most  recent  views,  it  would  seem 
as  if  the  Cretaceous  ancestors  of  the  Carnivora,  the  greaft 
order  to  which  the  dojg  tribe  belongs,  were  a  group  of  small 
arboreal  mammals  resembling  the  opossum  in  size  and 
habits,  while  more  nearly  allied  to  the  primitive  Insectivora. 
The  most  strictly  terrestrial  types,  such  as  the  Canidae  and 
Hyaenidae,  have  departed  widely  from  the  primitive  skeletal 
structure.  In  the  Eocene  we  already  find  several  families 
of  the  Carnivora  fully  developed,  one  of  which,  the  Miacidae, 
is  regarded  by  Dr.  Matthew  f  as  the  precursor  of  the  dog 
family. 

The  latter  originated  in  Oligocene  times,  but  it  was  not  until 
the  Miocene , Period  that, the  genus  Canis  marked  its  first 
appearance  in  America  and  Europe  simultaneously.  Since 
it  is  highly  improbable  that  the  same  genus  should  have  arisen 


*  Merriam,  0.  EL,  "Eevision  of  the  Coyotes." 

t  Matthew,  W.  D.,  "  Carnivora  and  Insectivora  of  the  Bridger,"  pp.  328 
—350. 


150  OEIGIN   OF   LIFE   IN   AMERICA 

independently  in  two  different  continents,  the  genus  Canis 
must  have  originated  either  in  America  or  Europe.  Dr. 
Matthew*  directs  attention  to  the  fact  that  the  modern  repre- 
sentatives of  the  Canidae  living  in  the  Oriental  region  and  in 
South  America  are  more  akin  to  the  Oligocene  and  lower 
Miocene  species  than  are  the  true  wolves,  jackals  and  foxes. 
Assuming  the  original  centre  of  evolution  to  have  been  some- 
where in  Europe  or  North  America,  we  might  argue  that  the 
older  types  of  dog -like  creatures  spread  into  distant  parts  and 
were  preserved  there,  while  they  were  superseded  in  their 
ancestral  home  by  more  modern  types. 

But  we  are  apt  to  forget  that  the  two  species  of  Canidae 
which  live  furthest  from  our  hypothetical  centre  of  origin 
are  most  nearly  related  to  what  we  generally  look  upon  as  the 
most  modern  of  the  dog  tribe.  I  am  alluding  to  the  wild  dog 
of  Australia  '(Canis  dingo)  and  to  the  Falkland  island  wolf 
(Canis  antarcticus) .  It  is  a  most  remarkable  fact  that  the 
latter  is  not  nearly  related  to  a  single  South  American  species 
of  the  dog  tribe,  whereas  it  really  belongs  to  the  coyotes  which, 
as  we  have  noticed  above,  are  confined  to  western  North 
America.  Similarly  the  Australian  dog,  which  is  now  gene- 
rally considered  a  truly  wild  species  and  not  a  recent  human 
introduction,  is  akin  to  one  of  the  European  Pleistocene  dogs. 
There  is  a  wild  dog  in  the  mountains  of  Java  (Canis  teng- 
gerana)  which  also  appears  to  be  nearly  related  to  the  dingo 
of  Australia.  These  two  anomalous  cases  do  not  seem  to  fit 
in  with  any  of  the  existing  theories.  Dr.  Wallace  f  main- 
tained that  it  must  have  been  as  far  back  as  the  Secondary 
Era  of  geological  history  that  Australia  was  in  actual  con- 
nection with  the  northern  continents,  and  received  from  the 
latter  the  ancestors  of  the  present  fauna.  There  was  no 
subsequent  land  connection,  according  to  Dr.  Wallace,  so  that 
from  that  remote  time  until  now  the  Australian  lands  have 
thenceforth  evolved  the  various  Marsupial  and  Monotreme 
types  which  we  now  find  there. 

It  is  evident  that  Dr.  Wallace  did  not  believe  in  the  indi- 
genousness  of  the  Australian  dog  when  he  made  these  remarks. 

*  Matthew,  W.  D.,  "  Lower  Miocene  Fauna  from  Dakota,"  p.  180. 
t  Wallace,  A.  K.,  "  Geographical  Distribution,"  I.,  p.  465. 


DISTRIBUTION   OF   RACCOONS  151 

Yet  even  those  who  do  are  at  a  loss  to  account  for  its  presence 
in  Australia.  Professor  Weber  *  favours  a  very  early  human 
introduction,  even  in  Pliocene  times.  I  myself  have  been 
unable  to  form  a  definite  judgment  on  this  subject. 

The  origin  of  the  Falkland  island  wolf  is  in  so  far  a  very 
much  more  difficult  problem  to  solve,  as  none  of  the  species 
of  the  dog  tribe  living  on  the  opposite  mainland  of  South 
America  are  at  all  nearly  related  to  it.  Dr.  Wallace'f  and  also 
Mr.  Lydekker  J  express  the  opinion  that  the  Falkland  islands 
were  evidently  connected  with  the  mainland  at  no  distant  date. 
Dr.  Wallace  believed  that  this  wolf  was  closely  allied  to  a 
Patagonian  species. 

Later  on  (p.  430)  I  shall  have  some  further  remarks  to 
make  on  this  subject.  I  only  mentioned  these  two  instances 
of  distribution  to  show  the  difficulties  which  we  frequently 
have  to  contend  with. 

The  ra-ccoon  (Procyon  lotor)  is  by  no  means  a  typical  in- 
habitant of  the  prairie,  still  as  it  occurs  here  and  there  and 
is  very  characteristic  of  North  America  it  may  as  well  be 
mentioned  here.  By  nature  a  forest  animal,  the  raccoon,  with 
its  omnivorous  propensities  and  great  adaptability,  easily  ac- 
customs itself  to  the  most  diverse  surroundings,  and  as  a 
rule  thrives  and  breeds  well  in  confinement.  It  inhabits  the 
whole  of  the  United  States  and  southern  Canada  and  belongs 
to  a  family  (Procyonidae)  which  is  quite  confined  to  North 
and  South  America,  and  always  has  been.  We  need  not  hesi- 
tate in  this  case  in  attributing  its  origin  to  America,  The 
raccoon  family  has  the  same  ancestors  (the  Early  Tertiary 
Miacidae)  as  the  dog  family,  according  to  Dr.  Matthew,  §  one 
of  the  members  of  the  former,  Cercoleptes  (Potos),  being 
actually  the  nearest  in  its  skeletal  construction  to  the  Eocene 
Miacidae.  It  has  been  stated  by  Dr.  Matthew  that  the  lower 
Miocene  Phlaocyon  from  Colorado  is  approximately,  though 
not  exactly,  ancestral  to  the  raccoon ;  but  in  view  of  the  fact 
that  both  Dr.  Ameghino  and  Dr.  von  Ihering  ||  emphatically 

*  Weber,  M.,  "  Der  Indo-australische  Archipel,"  p.  40. 

t  Wallace,  A.  E.,  "Geographical  Distribution,"  II.,  p.  49. 

t  Lydekker,  E.,  "  History  of  Mammals,"  p.  140. 

§  Matthew,  W.  D.,  "  Carnivora  and  Insectivora  of  the  Bridger,"  p.  331. 

||  Ihering,  H.  von,  "Siidamerik.  Eaubtiere,"  pp.  159—160. 


152  ORIGIN   OF   LIFE   IN   AMERICA 

support  its  being  one  of  the  dog  tribe  (Canidae),  we  should 
hesitate  before  accepting  the  earlier  opinion. 

The  genus  Procyon,  to  which  the  North  American  raccoon 
belongs,  only  makes  its  appearance  in  the  Pleistocene  Period. 
Nevertheless,  it  is  quite  possible  that  cave  deposits,  such  as 
that  described  from  McCloud  River  in  California  containing 
the  new  species  Procyon  sinus,  may  eventually  be  placed  in 
the  Pliocene  series.*  At  any  rate,  the  genus  Procyon  must 
have  existed  before  Pliocene  times,  and  it  seems  to  me  prob- 
able that  it  originated  either  in  South  America  or  in  some 
western  lands  which  have  long  since  subsided.  Dr.  von 
Ihering  f  believes  that  the  Procyonidae  have  undoubtedly 
come  from  eastern  Asia.  Why  he  should  think  so  I  cannot 
imagine,  for  neither  recent  nor  fossil  species  are  known  from 
that  continent. 

It  is  now  generally  admitted,  as  I  mentioned  already 
(p.  95),  that  Central  America  assumed  its  present  shape  and 
contours  at  some  time  during  the  Pliocene  Period  (compare 
p.  243).  As  soon  as  this  land  bridge  became  habitable  for 
terrestrial  animals,  northern  species  are  supposed  to  have 
poured  across  it  into  South  America.  We  possess  strong 
evidence  certainly  that  a  steady  stream  of  southern  animals 
invaded  the  northern  continent  in  Pliocene  and  even  in 
Pleistocene  times  and  that  northern  ones  succeeded  in  reach- 
ing the  south. 

The  group  of  the  so-called  toothless  mammals  (Edentata), 
comprising  the  ant-eaters,  sloths  and  armadillos,  are  almost 
entirely  confined  to  South  America;  and  that  continent  no 
doubt  is  their  original  home.  A  few  penetrated  in  some 
mysterious  manner  to  North  America  in  Eocene  times,  as  I 
shall  explain  more  fully  in  another  chapter.  Shortly  after- 
wards they  seem  to  have  become  extinct  again  in  North 
America,  for  no  traces  of  edentates  have  yet  been  discovered 
in  the  succeeding  Oligocene  deposits.  It  is  only  in  the 
Miocene  beds  of  North  America  that  we  again  meet  with 
examples  of  this  curious  group.  They  were  representatives 
of  the  huge  Megalonyx  which  is  closely  allied  to  a  southern 

*  Gidley,  J.  W.,  "  Fossil  Eaccoon  from  Calif ornian  Cave." 
t  Ihering,  H.  von,  "  Siidamerik.  Raubtiere,"  p.  160. 


CAVES   AND   THEIR   CONTENTS  153 

genus.  Megalonyx  and  Mylodon,  which  follows  in  Pliocene 
times,  were  giant  ground  sloths  almost  the  size  of  elephants, 
while  Glyptotherium,  another  Pliocene  species,  had  a  great 
shield -like  bony  armour  covering  the  whole  body.  The  plio 
cene  species  were  accompanied  by  a  great  peccary  (Platy- 
gonus),  a  llama  of  a  very  large  size  (Pliauchenia)  and  a 
number  of  other  interesting  creatures,  all  of  which  have  now 
completely  vanished  from  the  northern  continent. 

In  the  succeeding  deposits  from  the  great  plains  and  moun- 
tain regions,  which  have  been  classified  by  Professor 
Osborn  *  as  belonging  to  the  lower  Pleistocene  series,  we 
notice  the  remains  of  two  large  elephants  (Elephas  columbi 
and  E.  imperator),  a  true  camel  (Camelus)  and  two  other  mem- 
bers of  the  same  family,  the  great  peccary  Platygonus  and  the 
two  large  ground  sloths,  Mylodon  and  Paramylodon.  The 
rivers  were  tenanted  by  beavers,  otters,  musk  rats  and  a 
curious  semi -aquatic  creature  about  the  size  of  a  bear,  called 
Castoroides.  Belated  to  some  of  the  groups  of  South  American 
rodents,  the  latter  suddenly  makes  its  appearance  in  the 
Pleistocene  beds  of  eastern  North  America. 

Now  we  come  to  the  cave  deposits,  which  I  have  alluded  to 
already  on  several  occasions,  and  which  Professor  Osborn 
includes  in  the  middle  Pleistocene  or  Glacial  series.  The 
Port  Kennedy  cave  in  Pennsylvania  contains  no  less  than 
four  species  of  the  great  edentate  Megalonyx,  also  a  Mylodon, 
two  kinds  of  sabre -tooth  tigers,  a  Mastodon,  four  species  of 
peccaries  and  a  tapir.  In  the  Potter  Creek  cave  of  California 
were  discovered,  among  others,  four  species  of  Megalonyx,  a 
camel  and  a  Mastodon.  Finally,  the  Conard  fissure  of 
northern  Arkansas  revealed  two  species  of  sabre-tooth  tigers, 
three  kinds  of  peccaries  and  numerous  small  animals.  Apart 
from  a  few  deer  bones  and  the  remains  of  the  curious  Symbos^ 
an  animal  allied  to  the  musk  ox,  it  contained  no  traces  of  large 
ungulates.  Their  presence  in  the  district  adjoining  the  fissure 
is,  nevertheless,  indicated  by  the  sabre -tooth  tigers. 

What  I  wish  to  make  clear  is  that  huge  creatures  requiring 
an  abundance  of  vegetable  food  poured  into  North  America, 
not  only  in  Pliocene  but  also  in  Pleistocene  times.  Many 

*  Osborn,  H.  F.,  "  Cenozoic  Mammal  Horizons,"  p.  85. 


154  OKIGIN   OF   LIFE   IN   AMERICA 

other  mammals  apparently  had  their  original  home  in  this 
continent.  Peccaries  and  tapirs,  which,  as  we  know,  require 
a  hot  and  moist  climate,  lived  as  far  north  as  Pennsylvania 
even  during  the  time  when  vast  glaciers  were  supposed  to  have 
covered  the  whole  of  Canada  and  a  substantial  slice  of  the 
United  States.  We  are  told  that  the  fauna  of  .this  period 
clearly  reveals  the  state  of  the  climate.  If  the  remains  of  the 
animals  above  referred  to  indicate  anything,  they  show  us  un- 
doubtedly that  the  climate  was  mild,  with  an  abundance  of 
vegetation  and  animal  life.  In  common  with  most  other  geo- 
logists, Dr.  Hay  believes  that  the  climate  of  the  Glacial 
Epoch  must  have  been  cold  in  North  America,  because  he 
assumes  the  certain  existence  of  vast  ice-masses  at  that  time 
even  in  New  York,  in  Indiana  and  in  Missouri.  If  we  deal 
with  this  climatic  problem  from  an  independent  standpoint 
and  endeavour  to  reconstruct  the  conditions  prevailing  during 
the  Glacial  Epoch  from  purely  faunistic  evidence,  our  con- 
clusions cannot  point  to  the  prevalence  of  an  exceptionally 
cold  climate.  Proof  of  the  existence  of  a  cold  climate  in  the 
United  States  during  the  Pleistocene  Period  seems  to  be  fur- 
nished, says  Dr.  Hay,*  by  the  occurrence  of  the  three  genera 
of  mammals,  Kangifer,  Bootherium  and  Symbos. 

The  name  Bootherium  is  now  applied  to  an  extinct  large 
sheep-like  creature,  viz.,  B.  bombifrons,  whose  remains  have 
been  discovered  in  Pleistocene  deposits  of  Kentucky.  Accord- 
ing to  Dr.  Kowarzik  (see  p.  7),  Bootherium  was  probably 
the  direct  ancestor  of  the  northern  genus  Ovibos,  which  has 
never  been  found  in  any  Pleistocene  beds  in  the  United  States. 
Bootherium  can  scarcely  be  claimed  as  an  exponent  of  a 
cold  climate,. because  it  has  never  lived  north  of  the  United 
States.  The  latest  discoveries  seem  to  indicate  that  a  number 
of  sheep-like  animals  originated  in  the  United  States  towards 
the  latter  part  of  the  Pliocene  Period,  and  left  their  remains 
in  various  parts  of  the  country.  Thus  the  extinct  Eucera- 
therium,  first  identified  by  Dr.  Sinclair  and  Mr.  Furlong  from 
a  cave  in  California,  and  Preptoceras  from  another  Californian 
cave,  are  both  allied  to  Bootherium  and  Ovibos.  Hence  Ovibos 
is  the  sole  member  of  this  group  which  has  survived,  having 

*  Hay,  0.  P.,  "  On  the  Changes  of  Climate,"  p.  372. 


ON   EEINDEER  AND   CLIMATE  155 

succeeded  in  adapting  itself  to  an  arctic  habitat.  The  avail- 
able evidence  is  all  in  favour  of  a  gradual  advance  having 
taken  place  of  those  large  sheep-like  forms  from  a  more 
southern  to  a  northern  habitat  during  late  Tertiary  times. 
Mr.  Osgood  *  has  now  discovered  another  extinct  relation  of 
the  musk  ox  in  the  Yukon  Territory  of  north-western  Canada. 
He  first  described  it  as  Scaphoceros  tyrelli  (including  Ovibos 
cavifrons  of  Leidy  in  the  same  new  genus),  and  suggested 
that  Scaphoceros  may  be  ancestral  to  Ovibos.  According  to 
Mr.  Barnum  Brown,  the  name  Symbos  has  now  been  substi- 
tuted for  Scaphoceros.  Hence  Symbos  is  known  from  Indian 
Territory,  Iowa,  Missouri,  Ohio,  Pennsylvania,  Kansas, 
Arkansas,  from  Yukon  Territory  and  from  Alaska.  Yet  even 
its  former  presence  in  Alaska  cannot  stamp  Symbos  as  a  cold- 
loving  animal,  for  close  to  its  remains  were  dug  up  those  of 
a  Mastodon,  and  who  would  be  prepared  to  argue  that  the 
Mastodon  is  an  indicator  of  a  cold  climate  ? 

Lastly,  Dr.  Hay  claims  that  the  reindeer  (Rangif  er)  having 
occurred  so  far  south  of  its  present  habitat  (Fig.  10)  in 
Pleistocene  times  is  a  proof  of  the  existence  of  a  cold  climate 
at  that  time  in  the  United  States.  I  have  discussed  this  pro- 
blem once  before  (pp.  3 — 6),  but  I  may  add  a  few  remarks. 
If  the  drift  area  of  North  America  had  been  covered  largely  by 
the  sea,  as  I  believe  it  was,  during  part  of  the  Glacial  Epoch, 
the  country  which  was  still  habitable  for  the  reindeer  must 
have  been  greatly  reduced.  Hence  a  southward  emigration 
was  the  only  possible  chance  of  survival  for  some  herds  of 
reindeer.  Driven  out  of  their  home  by  the  stress  of  circum- 
stances, they  would  have  passed  into  a  district,  even  if  the 
latter  had  been  unsuitable  to  their  requirements.  At  any  rate, 
we  know  that  reindeer  can  live  perfectly  well  in  a  temperate 
climate  and  that  they  still  inhabited  Scotland  in  the  twelfth 
century  long  after  the  Glacial  Epoch  had  passed  away.  I 
cannot  therefore  consider  its  former  presence  in  the  United 
States  a  proof  of  a  cold  climate.  That  it  could  only  have 
penetrated  south  in  small  numbers  is  indicated  by  its 
total  absence  .from  all  the  North  American  caves  hitherto 
examined  except  one,  and  from  almost  all  the  other  Pleisto- 

*  Osgood,  W.  H.,  "  Scaphoceros  tyrelli,"  p.  178. 


156  OKIGIN   OF   LIFE   IN   AMERICA 

cene  deposits.  On  the  other  hand,  we  have  noted  that  pec- 
caries lived  in  the  United  States  during  the  Pleistocene  and 
the  preceding  .geological  periods.  They  were  not  exterminated 
by  the  severity  of  the  climate.  Representatives  of  the  peccary 
family  not  only  survived  the  Glacial  Epoch,  they  even  showed 
their  indifference  to  it  by  invading  the  area  which  had  only 
just  been  forsaken  by  the  supposed  Wisconsin  glacier,  for 
their  remains,  as  Dr.  Hay  tells  us,  were  found  in  deposits 
overlying  the  Wisconsin  drift  at  three  different  localities. 
In  the  single  cave  in  which  the  reindeer  occurred  its  re- 
mains were  mingled  with  those  of  a  species  of  peccary 
(Tayassus  tetragonus)  very  closely  allied  to  that  still  living 
in  the  Southern  States  and  in  South  America.  Nor  was  the 
Glacial  Epoch  any  more  trying  to  the  great  ground  sloth,, 
Megalonyx,  for  it  also  survived  it  and  invaded  the  area  covered 
by  the  drift.  The  remains  of  a  species  of  that  giant  edentate 
were  found  some  years  ago,  according  to  Dr.  Hay,  in  an  old 
filled -up  pond,  just  within  the  alleged  outermost  moraine  of 
the  Wisconsin  glacier  near  Millersburg  in  Ohio.  My  Own 
views  as  to  the  nature  of  the  climate  prevailing  during  the 
Pleistocene  Period,  and  particularly  during  that  phase  of  it 
known  as  the  "  Glacial  Epoch  "  or  Ice  Age,  are  derived  from 
a  careful  scrutiny  of  the  living  and  extinct  fauna  and  flora. 
This  study  of  the  animals  and  plants  does  not  reveal  to  me- 
that  the  Pleistocene  Period  was  a  period  of  extreme  cold. 
On  the  contrary,  as  I  remarked  before,  the  climate  seems  to 
have  been  milder  in  a  large  portion  of  the  northern 
hemisphere  than  it  is  at  present.  An  apparent  increase  of 
temperature  after  the  passing  away  of  the  "  Ice  Age  "  is 
supposed  to  he  indicated  by  the  appearance  of  forms  of  animal 
and  plant  life  requiring  a  higher  temperature  than  is  com- 
patible with  the  arctic  condition  believed  to  have  prevailed 
during  the  height  of  the  Glacial  Epoch.  It  is  really  due,  I 
think,  to  that  perfectly  natural  re-occupation  of  tracts  of 
country  on  which  both  plants  and  animals  had  been  destroyed. 
The  destructive  agent,  in  my  opinion,  was  not  ice  but  water. 
Glaciers  no  doubt  existed  on  all  the  higher  mountains  near 
the  Atlantic  and  Pacific  coasts.  They  owed  their  presence, 
however,  not  to  cold,  but  principally,  as  I  mentioned  before, 
to  the  higher  temperature  of  the  eastern  and  western  oceans. 


HELICINA  IN   NORTH   AMERICA  157 

Towards  the  latter  part  of  the  Glacial  Epoch,  when  the 
existing  geographical  conditions  of  the  northern  lands  were 
gradually  brought  about,  the  temperature  of  the  Atlantic  and 
Pacific  Oceans  decreased,  causing  a  diminution  of  precipita- 
tion on  the  continents.  With  slight  climatic  oscillations  the 
conditions  almost  all  over  the  northern  hemisphere  gradu- 
ally seem  to  have  grown  less  favourable  for  the  survival  of 
Tertiary  animals  and  plants  than  they  were  during  the  Ice 
Age.  Warmth  and  moisture-loving  species  are  almost  every- 
where being  replaced  by  others  that  can  support  greater 
extremes  of  temperature,  and  the  former  only  exist  here  and 
there  in  diminishing  colonies  as  relicts  of  the  past. 

In  the  United  States  we  have  evidence  of  such  a  course  of 
events,  not  only  among  the  higher  groups  such  as  the 
mammals;  some  of  the  more  slowly-moving  invertebrates 
are  even  more  trusty  indicators  of  the  past  geological  history 
of  the  country. 

Three  species  of  an  operculate  snail  belonging  to  .the  family 
Helicinidae  inhabit  the  United  States.  One  of  them(Helicina 
chrysocheila)  occurs  in  Texas  near  the  mouth  of  the  Rio 
Grande.  Another  (H.  orbiculata)  has  a  wide  range  from' 
Florida  and  Texas  as  far  north  as  Arkansas  and  Tennessee. 
A  third  (H.  occulta)  lives  in  isolated  colonies  among  loose 
leaf -mould  in  well-wooded  districts  from  Carolina  to  Wis- 
consin and  Minnesota.  Though  inhabiting  States  where 
severe  winter  frosts  are  common,  it  is  amply  protected  against 
them  by  its  mode  of  life.  Mr.  Cooke*  maintains  that  all 
operculate  land  mollusks  are  exceedingly  sensitive  to  cold, 
and  that  the  whole  group  is  undoubtedly  a  product  of  tropical 
or  semi-tropical  regions.  This  view  is  borne  out  by  the  range 
of  Helicina.  Far  to  the  west  of  North  America,  beyond  the 
Pacific  Ocean,  a,  few  stragglers  occur  in  Burma  and  on  the 
Nicobar  islands.  As  we  advance  eastward  they  increase  in 
number  in  certain  parts  of  southern  Asia.  Almost  throughout 
Polynesia  we  meet  with  some  species,  and  also  on  the  West 
Indian  islands  (Fig.  11).  That  the  genus  is  a  very  ancient 
one  must  be  evident  from  its  geographical  distribution.  It  had 
already  reached  America  in  early  Tertiary  times,  for  Dr.  Dall 

*  Cooke,  A.  H.,  "Molluscs,"  p.  24. 


158  OEIGIN   OF   LIFE    IN   AMERICA 

describes  a  species  from  the  Oligocene  Silex  beds  of  Tampa 
in  Florida  apparently  related  to  a  Helicina  still  inhabiting 
the  Bahama  islands.  Considering  that  the  genus  Helicina  is 
almost  confined  to  tropical  and  semi-tropical  countries,  we 
may  assume  that  it  spread  northward  at  a  time  when  very 
mild  climatic  conditions  prevailed  in  the  northern  United 
States,  and  that  a  few  more  hardy  species  have  survived  in 
isolated  colonies  wherever  they  could  obtain  sufficient  pro- 
tection against  frost.  This  view  is  confirmed  by  the  fact 
that  Helicina  occulta,  now  an  extremely  rare  shell,  is  abun- 
dant in  the  Pleistocene  loess  beds  of  Indiana,  Iowa  and 
Nebraska.  Mr.  Shimek  *  likewise  expressed  the  opinion  that 
the  still  existing  northern  colonies  of  Helicina  occulta  ap- 
pear to  be  the  remnants  of  a  once  common  race  which  is 
evidently  dying  out. 

A  family  which  resembles  the  Helicinidae,  in  so  far  as  it  is 
largely  confined  to  tropical  and  sub-tropical  regions,  is  that 
of  the  Phasmidae.f  They  comprise  orthopterous  insects  of 
the  shape  of  a  small  twig,  and  hence  are  known  as  "  walking 
sticks,"  also  "  prairie  alligators  "  or  "  stick-bugs  "  in  America. 
All  the  species  found  in  the  United  States  are  wingless.  They 
are  thus  not  liable  to  accidental  transport  except  perhaps  by 
water.  All  are  vegetable  feeders,  and  over  a  dozen  kinds 
inhabit  the  southern  States.  Among  these  walking-stick 
insects  there  is  one  which  has  a  remarkably  northern  range, 
viz.,  Diapheromera  femorata.  I  met  with  it  on  Goat  Island, 
above  the  Niagara  Falls.  It  has  also  been  observed  near 
Toronto,  and  several  other  places  in  southern  Canada.  We 
possess  no  fossil  evidence  of  the  geological  history  of  the 
genus  Diapheromera;  nevertheless,  the  fact  that  the  family 
Phasmidae  was  already  represented  in  Jurassic  times,  accord- 
ing to  Dr.  Handlirsch,J  justifies  the  assumption  that  Dia- 
pheromera originated  and  began  to  spread  northward  in  pre- 
Glacial  times,  and  that  it  may  be  regarded  as  a  southern  relict 
in  its  present  northern  habitat. 

Two  well-known  instances  of  survivals  of  southern  species 

*  Shimek,  B.,  "  Helicina  occulta." 

t  Caudell,  A.  N.,  "  The  Phasmidae  of  the  United  States,"  p.  874. 

|  Handlirsch,  A.,  "  Die  Fossilen  Insekten,"  p.  1191. 


FIG.  11. — Map  of  North  and  South  America,  showing  the  distribution  (in  black  and 
within  the  area  surrounded  by  small  circles)  of  the  snail  Helicina. 


\Jfoface  p.  158. 


TUEKEYS  AND  PAEEOTS         159 

of  birds  in  northern  habitats  occur  to  me.  Strictly  speaking, 
they  should  not  be  quoted,  because  they  are  now  extinct  in 
their  northern  habitats.  But  as  tlheir  extermination  happened 
within  historic  times,  and  has  been  caused  by  human  interfer- 
ence, I  may  venture  to  include  them  in  this  group  of  southern 
invaders.  They  are  the  turkey  and  the  Florida  parrot. 

The  wild  turkey  (Meleagris  gallopavo)  belongs  to  a  dis- 
tinctly southern  group  of  birds.  In  the  time  of  the  early 
settlers  it  was  common  as  far  north  as  Massachusetts,  and 
extended  westward  to  Colorado  and  southward  to  Mexico  and 
Florida.  Being  a  much-prized  luxury  of  the  pioneer  hunter, 
it  was  soon  exterminated  in  the  more  populous  districts.  It 
still  occurs  in  some  of  the  southern  States,  while  an  allied 
species  is  known  from  Central  America.  The  genus  Meleagris 
was  already  an  inhabitant  of  North  America  in  Oligocene 
times,  for  Prof essor  Marsh  described  a  species  from  the  White 
River  deposits  in  Colorado.  No  doubt  it  has  lived  in  North 
America  ever  since  those  early  Tertiary  times.  All  we  know 
from  fossil  evidence  is  that  the  remains  of  two  other  species 
were  identified  from  Pleistocene  deposits  in  New  Jersey,  while 
the  bones  of  the  wild  turkey  itself  have  been  noticed  in  a  cave 
in  Pennsylvania.  Like  the  edentates  and  peccaries  this 
southern  genus  of  birds  flourished  in  the  northern  States 
throughout  the  Glacial  Epoch  and  survived  there  until  his- 
toric times. 

The  Florida  parrot  (Conuropsis  carolinensis)  is  the  only 
example  of  the  large  parrot  tribe  indigenous  to  the  United 
States.  It  is  now  restricted  to  the  comparatively  small  area 
of  the  Gulf  States  and  the  lower  Mississippi  Valley.  Yet  the 
early  settlers  noticed  this  bird  even  near  the  shores  of  the 
Great  Lakes,  and  occasionally  it  was  observed  near  the  cities 
that  were  springing  up  in  the  eastern  States.  No  doubt  it 
survived  in  these  northern  districts  from  remote  times,  al- 
though we  possess  ,no  fossil  evidence  of  this  fact.  It  cannot 
be  contended  that  the  parrot  left  its  former  habitat  through 
persecution ;  nevertheless,  man  in  his  agricultural  pursuits, 
must  have  interfered  with  it,  possibly  by  reducing  the  birds' 
food  supply. 

I  wish  now  to  make  a  few  remarks  on  the  inhabitants  of 
the  mighty  river  and  its  tributaries  flowing  through  the 


160  ORIGIN   OF   LIFE   IN   AMERICA 

continental  basin,  as  they  are  of  such  importance  in  tracing 
the  geological  history  of  the  fauna.  The  Mississippi  lies 
wholly  within  the  boundaries  of  the  United  States,  and  drains 
more  than  two -fifths  of  their  area.  Originating  in  Lake  Itasca 
in  Minnesota,  the  Mississippi  receives  during  its  long  course 
four  great  tributaries,  the  Missouri,  Ohio,  Arkansas  and  Red 
River,  and  a  large  number  of  smaller  ones.  The  two  prin- 
cipal groups  of  animals  inhabiting  this  great  river  system  are 
the  fishes  and  fresh-water  mussels.  Some  of  the  fishes  are 
able  to  live  in  brackish  water,  others  spend  part  of  their 
lives  in  the  sea,  so  that  they  are  not  of  such  extreme  im- 
portance from  a  zoogeographical  point  of  view  as  the  fresh- 
water mussels. 

Fresh-water  mussels,  or  Naiades  as  they  have  been  called, 
all  die  quickly  if  immersed  in  salt  water  or  if  removed  to  the 
land.  Their  distribution  being  world-wide,  they  have  been 
looked  upon  by  some  naturalists  as  among  the  best  indicators 
of  former  changes  of  land  and  water  over  the  globe.  Others 
have  urged  that  the  wide  range  of  these  mussels  may  be  due  to 
accidental  conveyance  by  birds  or  fishes.  It  was  thought 
that  the  eggs  or  the  newly-hatched  fry  of  the  mussels  had 
been  thus  transported.  Many  species  immediately  after  their 
fry  has  been  hatched  from  the  eggs,  develop  booklets  on  the 
temporary  shell,  by  which  the  young  mussels  can  attach 
themselves  to  foreign  objects.  It  has  been  argued  that  such 
larval  mollusks  might  become  attached  to  the  feet  of  aquatic 
birds  and  be  carried  by  them  in  their  flight  from  the  fresh 
waters  of  one  region  to  those  of  other  regions  and  there  be  set 
free.  Theoretically,  such  an  accidental  transport  would  seem 
quite  a  possible  one  from  time  to  time,  certainly  much  more 
likely  than  a  similar  conveyance  of  the  fry  by  fishes  from  one 
river  sys'tem  to  another.  In  a  country  like  North  America, 
where  millions  of  migratory  birds  pass  annually  north  and 
south,  and  to  some  extent  east  and  west,  the  effects  of  a  con- 
veyance such  as  suggested  should  be  clearly  discernible  in  the 
composition  of  the  North  American  fresh -water  mussel  fauna. 
Yet  although  there  are  over  four  hundred  different  kinds  of 
fresh-water  mussels  in  the  Mississippi  drainage  area,  some 
of  them  having  existed  there  almost  unchanged  since  Cre- 
taceous times,  the  fauna  to  the  east  and  west  of  that  area  is 


FEESH-WATER  MUSSELS  161 

entirely  different.*  The  geographical  distribution  of  fresh- 
water mussels  in  North  America  thus  constitutes  a  practical 
demonstration  of  the  correctness  of  the  view  so  ably  main- 
tained by  Dr.  von  Ihering,f  and  supported  by  Dr.  White, 
that  these  mollusks  are  not  appreciably  affected  by  chance  or 
accidental  dispersal. 

The  family  Unionidae,  to  which  all  the  North  American 
fresh -water  mussels  belong,  first  appeared  during  the  Triassic 
Age.  Their  principal  diffusion  over  the  globe  may  possibly 
have  been  effected  in  Secondary  or  Mesozoic  times.  During 
the  closing  period  of  the  Mesozoic  Era,  the  Cretaceous,  the 
family  attained  an  extraordinary  development,  particularly 
in  the  Laramie  strata.  The  remarkable  feature  is  that  many 
of  the  species  in  these  beds  are  so  nearly  like  the  living 
species  that  according  to  Professor  Whitfield  J  they  are  to  all 
intents  a,nd  purposes  the  same.  There  were  at  that  time 
(the  Cretaceous  Period)  two  great  land  masses  in  place  of  the 
North  American  continent  viz.,  one  in  the  east,  the  other 
in  the  west.  The  fresh-water  mussel  fauna  occupied  then 
as  far  as  we  know,  mainly  the  eastern  flank  of  the  western 
land-mass.  The  latter  was  probably  connected,  as  I  shall 
endeavour  to  show  later  on,  with  some  old  land-masses  on 
the  west  coast  of  South  America.  South  America  may  thus 
have  acquired  its  Unionidae  in  Mesozoic  times. 

The  two  great  families  of  fresh-water  mussels,  Unionidae 
and  Mutelidae,  have  been  recognised  for  some  time  past,  also 
the  restriction  in  distribution  of  the  latter  family  to  Africa 
and  South  America.  It  was  not  until  the  year  1891  that 
Dr.  von  Ihering  §  made  the  striking  discovery  that  all  the 
Unionidae  begin  their  existence  on  hatching  from  the  egg,  as 
so-called  "  glochidium  "  larvae,  while  the  Mutelidae  have  an 
entirely  different  "lasidium"  larva.  The  Unionidae,  of 
which  about  one  thousand  species  are  now  known,  have  since 
been  subjected  to  a  thorough  critical  revision  by  Dr.  Simp- 


*  White,  Charles  A.,  "  Ancestral  Origin  of  North  American  Unionidae," 
pp.  77—79. 

t  Ihering,  H.  von,  "  Najaden  von  S.  Paulo,"  pp.  133—140. 

J  Whitfield,  E.  P.,  "Fossil  Unionidae  from  Laramie  Clays,"  p.  624. 

§  Ihering,  H.  von,  "  Anodonta  and  Glabaris." 

L.A.  M 


162  ORIGIN   OF   LIFE   IN   AMERICA 

son,*   as   a    result     of   which   we   now   recognise   sixty-one 
genera. 

To   return   to   the   strictly   North   American   fresh-water 
mussels,    it  has   heen   found   that   a    common    assemblage 
inhabits  the  entire  Mississippi  drainage  basin,  and  that  a 
considerable  number  of  the  species  have  a  distribution  cover- 
ing the  greater  part  of  this  area,  as  well  as  <the  whole  of 
Texas  and  even  parts  of  eastern  Mexico.     The  streams  which 
fall  into  the  Atlantic  are  peopled  by  an  entirely  different  set 
of  forms,  the  Appalachian  chain  seeming,  according  to  Dr. 
Simpson,  to  act  as  a  sharp  barrier  between  the  two  regions. 
In  the  greater  part  of  Mexico  and  Central  Am'erica  a  totally 
different  fresh-water  mussel  fauna  is  found.       Two  Unios, 
one  Margaritana  and  some  half-a-dozen  Anodons,  are  all  that 
have  hitherto  been  credited  to  the  immense  region  on  the 
Pacific  slope  of  North  America.     One  of  the  Unios,  says 
Dr.   Simpson,t  has  been  recorded  in  error,  the  other  is  a 
form  of  the  most  abundant  and  most  widely  distributed  Unio, 
viz.,  U.  luteolus.     The  causes  which   led  to  this  striking 
difference   between   the    fresh -water   mussel    fauna   of   the 
Central  basin  and  that  of  the  Pacific  slope  will  be  discussed 
in  another  chapter.     I  may  only  mention  that  a  somewhat 
similar  disparity  between  the  two  faunas  has  been  observed 
among  the  fresh-water   fishes.     Before  dealing    with  these 
there  is  one  other  matter  of  importance  that  I  should  like 
to  refer  to  in  connection  with  the  geographical  distribution 
of  fresh-water  mussels. 

The  far-reaching  results  of  the  study  of  the  geographical 
distribution  of  such  a  group  as  the  fresh-water  mussels  is 
exemplified  in  a  striking  manner  by  the  following  physio- 
graphic problem.  In  discussing  the  origin  and  recent  history 
of  the  physical  features  of  the  southern  Appalachians 
Messrs.  Hayes  and  Campbell  advocated  the  theory  that  the 
upper  Tennessee  river,  now  a  tributary  of  the  Ohio,  formerly 
flowed  into  the  Gulf  of  Mexico  by  way  of  the  existing  Coosa 
and  Alabama  Rivers.  The  conclusions  were  based  entirely 

*  Simpson,  C.  T.,  "  Synopsis  of  the  Naiades." 

t  Simpson,  0.  T.,  "  Relationship  and  Distribution  of  Unionidae," 
pp.  354—358. 


BQNY-PIKE    AND   BOW-FIN  163 

upon  physiographic  evidence — such  as  the  character  of  the 
Tennessee-Coosa  divide,  the  nearness  of  the  gorge  below 
Chattanooga,  and  the  general  arrangement  of  the  drainage 
lines.  *  Now  it  is  a  remarkable  fact  that  Dr.  Simpson  has  quite 
independently  come  to  a  similar  conclusion  from  a  study  of 
the  fresh -water  mussels.  The  upper  Tennessee  and  also  the 
Alabama  River  abound  in  species  of  the  genus  Pleurobema, 
which  is  quite  absent  in  the  lower  Mississippi.  The  species, 
moreover,  found  in  these  two  rivers  are  very  closely  allied,  so 
that  this  and  other  characters  led  Dr.  Simpsonf  to  the  con- 
viction that  at  some  time  in  the  middle  or  later  Tertiary,  the 
Tennessee  River  must  have  flowed  southward  into  some  of 
the  streams  of  the  Alabama  drainage,  discharging  its  waters 
in  this  manner  direct  into  the  Gulf  0:f  Mexico. 

In  the  fourth  chapter  (p.  88)  I  cited  some  ganoid  fishes 
of  the  Mississippi  in  illustration  of  the  zoological  relation- 
ship existing  between  eastern  North  America  and  eastern 
Asia.  Two  other  well-known  and  very  remarkable  ganoid 
fishes  live  in  the  Mississippi  basin,  viz.  the  bow-fin  (Amia 
calva)  and  the  bony-pike  (Lepidosteus  osseus).  The  former 
is  the  sole  surviving  member  of  the  family  Amiidae.  Long 
ago,  in  early  Tertiary  times,  the  genus  Amia  inhabited  middle 
and  western  Europe,  while  it  is  amply  represented  in  the 
Eocene  (Bridger)  deposits  of  Wyoming.  Bony-pikes  lived  in 
Europe  from  Eocene  to  Mio»cene  times.  In  America  they 
likewise  appeared  in  the  Eocene  period,  and  persisted  until 
the  present  day.  It  is  evident  that  both  the  bow-fin  and  bony- 
pike  are  extremely  ancient  types,  which  have  managed  to 
survive  a  great  many  geological  changes  of  the  American 
continent.  Their  ancestors  must  have  travelled  to  Europe 
in  the  dawn  of  the  Tertiary  Era,  assuming  of  course  that 
North  America  was  the  birthplace  of  these  genera.  Did 
they  travel  from  river  to  river  and  from  lake  to  lake  across 
North  America  and  Asia  to  Europe,  or  did  they  utilise  the 
fresh-water  streams  of  a  shorter  direct  land  bridge  to 
Europe  ?  These  are  problems  to  be  solved.  The  zoological 

*  Hayes,  0.  W.,  and  M.  E.  Campbell,  "  Eelation  of  Biology  to  Physio- 
graphy,"  p.  131. 

t  Simpson,  0.  T.,  "  Evidence  of  Unionidae,"  pp.  134—135. 

M  2 


164  ORIGIN   OF   LIFE   IN   AMERICA 

affinity  between  Europe  and  North  America  is  so  strong, 
and  already  so  many  instances  of  this  relationship  have  been 
referred  to,  that  nothing  short  of  a  wide  and  convenient  land 
bridge  with  lakes,  rivers  and  mountains  will  suffice  to  ex- 
plain the  meaning  of  the  palaeontological  facts.  All  we  know 
is,  that  in  early  Tertiary  times  these  fishes  multiplied  and 
migrated  from  their  original  centre  of  dispersal.  The  genus 
of  the  bow-fin  is  all  but  extinct.  Only  a  single  species 
remains.  The  bony-pikes  exhibit  a  little  more  vitality,  no 
less  than  three  species  being  still  living.  The  common  form 
(Lepidosteus  osseus)  ranges  from  the  Great  Lakes  to  Vermont 
in  the  east,  and  from  there  south-westward  as  far  as  Mexico. 
A  much  larger  bony-pike  lives  in  the  southern.  States,  in 
north-eastern  Mexico  and  in  the  island  of  Cuba,  while  'a 
smaller  species  (L.  tropicus)  has  been  observed  in  Tabasco, 
Guatemala,  Nicaragua  and  Panama.*  If  Lepidosteus  were  a 
fish  directly  limited  to  fresh  water,  we  might  argue  that  at 
some  remote  time  in  the  past,  a  land  mass  extended  from 
Mexico  to  Cuba  and  southward  to  Panama,  but  being  occa- 
sionally met  with  in  brackish  water  it  is  possible  that  bony- 
pikes  can  traverse  short  distances  by  sea.  We  cannot  for  this 
reason  base  any  conclusions  regarding  minor  changes  of  land 
and  water  on  the  present  distribution  of  these  fishes.  Never- 
theless it  is  a  significant  fact  that  the  western  States  '.are 
devoid  of  bony-pikes  and  perches  as  they  almost  are  of  fresh- 
water Unios. 

Besides  the  Mississippi  fauna,  the  curious  dwellers  of  sub- 
terranean waters  in  the  Mississippi  drainage  area  throw  a 
certain  amount  of  light  on  the  past  conditions  of  the  country. 
A  brief  account  of  them  at  any  rate  will  be  of  interest  before 
concluding  this  chapter. 

I  believe  Mr.  Putnam  f  was  the  first  to  exhibit  a  collection 
of  blind  fishes  and  crustaceans  from  the  Mammoth  Cave  to  a 
scientific  meeting.  In  doing  so  he  expressed  the  opinion 
that  most  of  the  animals  inhabiting  the  cave  are  of  compara- 
tively late  introduction,  since  they  are  closely  allied  to  forms 


*  Eegan,  0.  Tate,  "Biologia  Centrali- Americana,"  p.  181. 
t  Putnam,  F.  W.,  "Mammoth  Cave  and  its  Inhabitants,"  pp.  194— 
195. 


BLIND   ANIMALS  165 

living  in  the  vicinity  of  the  cave.  Nevertheless  he  claimed 
for  the  blind  fishes  and  some  of  the  invertebrates  a  different 
origin,  because  the  former  had  no  immediate  relations  among 
fresh-water  forms,  while  the  lernean  fish  parasite  was  a 
more  decidedly  marine  than  fresh -water  form.  He  took  these 
facts  to  indicate  that  part  of  the  great  cave  system  was 
supplied  by  marine  life. 

Professor  Packard  *  makes  no  allusion  to  Mr.  Putnam's 
view  in  his  account  of  the  origin  of  the  subterranean,  fauna 
of  North  America.  Mr.  Putnam's  theory  indeed  appears  to 
be  scarcely  tenable.  His  remark  that  the  blind  fishes  of  the 
Mammoth  and  other  caves  have  no  immediate  relations  among 
fresh-water  forms  has  to  be  modified  in  accordance  with  our 
existing  knowledge  of  fishes.  The  blind  fishes,  all  of  which 
belong  to  the  family  Amblyopsidae,  are  no  doubt  a  very 
ancient  group,  and,  as  Drs.  Jordan  and  Evermannf  suggest 
they  are  probably  descendants  of  the  eyed  genus  Chologaster, 
or  at  least  forms  very  closely  allied  to  it.  Now  one  species 
of  Chologaster  inhabits  swampy  marshes  in  the  southern 
States,  and  two  others  live  in  the  subterranean  streams  of 
Tennessee,  Kentucky  and  Illinois.  The  most  typical  blind 
fishes,  Typhlichthys  subterraneus  and  Amblyopsis  spelaeus, 
are  met  with  in  the  underground  streams  of  Indiana  and 
Kentucky. 

Professor  GarmanJ  expressed  the  opinion  that  the  blind 
species  observed  in  the.  caves  were  already  blind  prior  to  the 
formation  of  the  caves,  and  that  they  only  collected  there 
from  various  directions  owing  to  the  favourable  conditions 
for  their  requirements.  Whether  this  theory  is  based  on  sound 
evidence  need  not  be  discussed,  but  his  statement  that 
Typhlichthys  subterraneus  has  a  very  wide  range  has  been 
questioned  by  Professor  Eigenmann,§  who  showed  that  the 
apparently  identical  species  from  Missouri  is  really  quite 
distinct  from  that  of  the  Mammoth  Cave.  Professor  Eigen- 
mann  points  out  that  we  have  to  deal  with  a  remarkable  and 

*  Packard,  A.  S.,  "  Origin  of  subterranean  fauna." 
t  Jordan,  D.  S.,  and  B.  W.  Evermann,  "  Fishes  of  North  America," 
Vol.  L,  p.  702. 

J  Garman,  H.,  "  Origin  of  Cave  Fauna,"  pp.  240—241. 
§  Eigenmann,  C.  H.,  "A  Case  of  Convergence,"  p.  281. 


166  ORIGIN   OF   LIFE   IN   AMEEICA 

instructive  case  of  convergence.  The  two  very  distinct  forms 
have  converged  because  of  the  similarity  of  their  environ- 
ment, and  especially  owing  to  the  absence  of  those  elements 
in  their  environment  that  lead  to  external  protective 
adaptations. 

The  family  Amblyopsidae  is  confined  to  North  America, 
and  its  nearest  relations  are  no  doubt  the  Poeciliidae,  a  group 
of  fresh-water  fishes  with  a  wide  distribution  in  America, 
southern  Europe,  Asia  and  Africa.  There  are  therefore  no 
grounds  for  the  supposition  that  the  blind  fishes  of  the  sub- 
terranean waters  of  North  America  are  descended  from 
marine  ancestors. 


CHAPTER  VIII 

THE    SOUTH-EASTERN    STATES 

THE  inhabitants  of  the  south-eastern  States,  which  I  shall 
endeavour  to  describe  in  this  chapter,  form,  in  many  respects, 
a  great  contrast  to  those  of  the  continental  basin.  The  greater 
humidity  of  the  Atlantic  States  produces  that  characteristic 
wealth  and  profusion  in  floral  life  which  constitutes  so  at- 
tractive a  feature  as  we  approach  the  ocean  from  the  west. 
And  no  one  can  fail  being  struck  by  the  change  in  vegetation 
even  in  travelling  southward  through  the  Atlantic  States  from 
the  north.  The  oaks,  chestnuts  and  hickories  become  more 
varied,  evergreens  of  all  kinds  increase  in  number,  new  and 
magnificent  magnolias  make  their  appearance,  while  vines 
and  creepers  mingle  their  foliage  with  that  of  shrubs  and 
trees.  The  splendid  white  pine  of  the  north  is  replaced  in 
the  south  by  the  long-leaved  yellow  pine,  whose  hard,  strong 
and  durable  wood  serves  such  a  wide  range  of  uses.  We  also 
notice  an  entirely  new  conifer,  the  cypress,  which,  like  the 
tamarack,  sheds  its  leaves  in  the  autumn.  Further  south  in 
Florida,  still  greater  changes  await  us,  and  in  the  extreme 
tip  of  that  peninsula  we  are  surrounded  by  tropical  vegeta- 
tion. Low  fan  palms  and  the  palmetto  grow  even  further 
north,  but  here  we  meet  for  the  first  time  with  the  royal  palm, 
which  for  height  and  grace  of  shape  is  unequalled,  and  many 
other  characteristic!  denizens  of  the  tropics.  Indeed,  as  Mr. 
Brendel  *  points  out,  the  flora  of  southern  Florida  should  not 
be  looked  upon  as  part  of  the  North  American  flora  but  as  a 
link  between  it  and  that  of  the  West  Indies.  Over  two  hundred 
and  thirty  species  of  plants  do  not  extend  north  of  Tampa, 
whereas  southern  Florida  has  one  hundred  and  eighty  seven 
in  common  with  the  West  Indian  Islands. 

This  affinity  between  the  floras  of  southern  Florida  and 

*  Brendel,  F.,  "  Notes  on  the  Flora  of  Florida,"  p.  449. 


168  ORIGIN   OF   LIFE   IN   AMERICA 

the  Antilles  is  generally  believed  to  be  due  to  accidental  dis- 
persal. The  seeds  of  these  plants  are  supposed  to  have  been 
conveyed  to  southern  Florida  from  the  West  Indian  Islands 
by  winds,  ocean  currents  or  migratory  birds.  Professor 
Engler,*  for  instance,  argues  that  a  direct  land  connection 
between  the  West  Indies  and  North  America  by  way  of  Florida 
could  never  have  eixsted,  because  the  latter  had  been  sub- 
merged beneath  the  sea  until  the  end  of  Tertiary  times, 
and  that  seeds  are  easily  conveyed  to  Florida  by  the  branch 
of  the  Gulf  Stream  sweeping  along  the  northern  shore  of 
Cuba  in  a  north-eastward  direction,  carrying  quantities  of 
vegetable  matter  and  often  even  tree  trunks.  Winds  could 
only  transport  such  seeds  that  are  specially  adapted  for  long 
flights.  As  regards  migratory  birds,  which  are  popularly 
believed  to  carry  seeds  to  great  distances  in  their  crops 
and  among  their  feathers,  it  may  be  pointed  out  that 
the  main  highway  for  birds  travelling  between  the  eastern 
States  and  South  America  is  by  way  of  north-western 
Florida  and  Cuba,  and  not  by  southern  Florida. f  If 
birds  had  any  special  influence  in  the  transport  of  seeds,  not 
the  southern  portion  of  Florida  but  the  northern  one  should 
show  affinities  in  the  flora  with  the  West  Indies.  If  the 
resemblance  in  the  vegetation  of  southern  Florida  and  the 
Antilles  were  mainly  due  to  the  Gulf  Stream,  we  should  expect 
to  find  the  most  pronounced  similarity  between  the  two  floras 
among  the  strand  plants  of  Florida.  This  is  not  the  case. 
The  great  majority  of  the  flowering  plants  now  known  to  be 
common  to  the  West  Indies  and  North  America  occur  in  what 
is  called  the  "  hummocks  "  of  the  southern  extremity  of 
Florida.  These  hummocks  consist  of  isolated  groups  of  hard- 
wood trees,  shrubs  and  vines,  and  are  scattered  like  islands 
in  the  everglades  and  pine  forests,  instead  of  being  surrounded 
by  the  ocean.  Moreover,  the  flora  of  southern  Florida  is  by 
no  means  exclusively  West  Indian  in  character.  About  forty 
species  of  plants  are  peculiar  to  southern  Florida,  and  over 
twenty  are  found  elsewhere  only  in  Mexico.  J 

*  Engler,  A.,   "  Entwicklungsgeschichte  d.  Florengebiete,"  II,  p.  215. 
t  Cooke,  W.  W.,  "New  Facts  about  Migration  of  Birds,"  p.  376. 
|  Harshberger,  J.  W.,  "  Floristic  Elements  of  Eastern  North  America," 
p.  612. 


VEGETATION   OF   FLORIDA  169 

A  West  Indian  fauna,  too,  is  associated  with  the  flora  in  this 
portion  of  the  United  States,  as  will  be  shown  later  on.  The 
problem  presented  by  the  origin  of  this  tropical  element  in 
the  North  American  flora  at  any  rate  is  not  quite  so  simple 
as  It  appears  at  first  sight.  Dr.  Harshberger  is  of  the  opinion, 
that  the  hummock  lands  on  which  the  tropical  flora  principally 
grows  represent  part  of  an  ancient  system  of  islands  which 
existed  at  a  time  when  the  Gulf  Stream  passed  fight  across 
the  then  submerged  portion  of  northern  Florida.  We  might, 
therefore,  make  further  enquiries  as  to  whether  this  theory  is 
supported  by  geological  or  other  evidence,  before  taking  for 
granted  that  the  tropical  element  in  the  fauna  and  flora  of 
Florida  is  of  purely  accidental  origin. 

Professor  Shaler  *  informs  us  that  along  the  coast  of 
Florida,  both  on  the  eastern  or  Atlantic  and  the  western  or 
Gulf  side,  there  arise  from  beneath  the  sea  a  number  of 
submarine  springs.  They  thus  discharge  great  tides  of  fresh 
water,  originally  gathered  on  the  land,  through  openings  on 
the  floor  of  the  ocean.  He  argues  that  these  springs  probably 
shed  their  waters  along  the  margin  of  the  sea  above  high  water 
level,  and  remarks,  "  I  cannot  conceive  any  such  under- 
ground waterways  to  have  been  produced  under  the  existing 
conditions  of  land  and  water."  He  assumes  consequently,  that 
Florida,  or  a  certain  part  of  it  at  any  rate,  must  have  stood 
at  a  higher  level  in  relation  to  the  sea  than  it  does  now  within 
comparatively  recent  geological  times. 

Through  the  discovery  of  a  submerged  system  of  drainage- 
valleys  off  the  coasts  of  Florida  and  the  Antilles,  Dr. 
Spencer  is  led  to  believe  in  an  elevation  of  this  area  during 
the  earlier  part  of  the  Pleistocene  Period  to  the  extent  of 
8,000  to  12,000  feet  or  more.  During  a  subsidence  which 
followed,  according  to  the  same  author,  the.  greater  part  of 
the  existing  peninsula  of  Florida  was  submerged.  Dr. 
Spencer  f  does  not  specify  what  parts  of  it  remained  above 
water,  but  presumably  the  whole  of  the  southern  Florida 
which  is  low-lying  was  included  in  the  submerged  portion.  If 


*  Shaler,  N.  S.,  "  Nature  and  Man  in  America,"  pp.  104—106. 
t  Spencer,  J.  W.,  "  Becon  struct  ion  of  Antillean  Continent,"  pp.  128— 
129. 


170  OBIGIN   OF  LIFE   IN  AMERICA 

the  tropical  flora  had  gained  admission  to  southern  Florida 
during  its  supposed  land  connection  with  the  West  Indies 
in  lower  Pleistocene  times,  it  would  have  besn  all  destroyed 
again  subsequently.  If  Dr.  Spencer's  theory  were  substan- 
tiated, the  tropical  flora  of  Florida  should  owe  its  origin  to 
accidental  transport. 

When  Dr.  E.  A.  Smith  *  visited  Florida  in  1880  he  made 
some  geological  notes  on  the  peninsula  which  do  not  bear  out 
Dr.  Spencer's  views.  He  maintains  that  Florida  was  elevated 
nearly  to  its  present  height  above  sea-level  after  the  deposi- 
tion of  the  Vicksburg  limestone,  that  is  to  say,  after  the 
Eocene  Period,  and  that  this  elevation  persisted  until  the 
Pleistocene,  when  the  country  was  partly  submerged. 

No  one,  however,  has  done  more  practical  geological  work 
on  the  peninsula  than  Dr.  Dall,f  who,  in  his  monumental 
treatises  on  the  Tertiary  fauna  of  Florida,  presented  us  with 
a  masterly  survey  of  the  past  life  of  that  portion  of  the  United 
States.  His  opinion  on  the  geological  history  of  Florida 
deserves,  therefore,  most  serious  consideration,  and  it  may  be 
stated  at  onc'e  that  he  is  strongly  opposed  to  Dr.  Spencer's 
views,  declaring  them  to  be  "  incompatible  with  every  geologic 
and  palaeontologic  fact  of  South  Florida  which  has  come  to 
my  knowledge." 

As  the  result  of  his  researches  Dr.  Dall  expresses  the 
opinion  that  the  peninsula  of  Florida,  together  with  the  larger 
Antillean  Islands  and  the  Middle  American  highlands,  were 
uplifted,  and  the  two  Americas  thus  united  in  OligO'Cene 
times,  that  is  to  say,  during  the  early  part  of  the  Tertiary 
Era. 

Professor  Gregory  J  had  a  similar  idea,  except  that  he  did 
not  specify  any  geological  period. 

When  Florida  again  became  disconnected  from  this  Antil- 
lean continent  is  not  clearly  stated,  but  Dr.  Dall  thought 
that  it  formed  a  peninsula  of  the  southern  continent  as  it 
does  now  of  the  northern.  Florida,  according  to  the  same 
author,  became  definitely  united  to  North  America  towards 

*  Smith,  E.  A.,  "Geology  of  Florida,"  p.  306. 

t  Dall,  W.  H.,  "Tertiary  Fauna  of  Florida,"  IV.,  p.  1546. 

I  Gregory,  J.  W.,  "  Geology  of  West  Indies,"  p.  305. 


GEOLOGICAL   HISTOKY   OF   FLOKIDA  171 

the  end  of  the  Miocene  Period,  while  a  slight  depression 
occurred  in  Pliocene  times,  and  little  change  since.  Whether 
the  tropical  flora  of  southern  Florida,  or  part  of  it  at  any  rate, 
is  the  relict  of  an  Oligocene  invasion  from  the  south  is  left 
undetermined  by  Dr.  Dall's  researches.  Yet,  from  the  fact 
that  a  species  of  the  terrestrial  mollusk  Glandina  occurs  in 
the  Pliocene  Caloosahatchie  beds  of  south-western  Florida, 
we  might  be  led  to  infer  that  other  southern  forms  might 
have  survived  on  the  peninsula  till  Pliocene  and  possibly 
recent  times. 

Dr.  Hill  concurs  in  so  far  with  Dr.  Dall's  conclusions 
as  he  establishes  in  Jamaica  signs  of  a  tremendous  orogenic 
movement  in  late  Oligocene  or  Miocene  times,  resulting  in  an 
uplift  whereby  many  of  the  West  Indian  Islands  and  pos- 
sibly an  insular  southern  portion  of  Florida  became  united 
with  one  another.  In  Miocene  or  early  Pliocene  the  islands, 
according  to  Dr.  Hill,*  were  severed  from  one  another  by 
submergence,  assuming  gradually  their  present  outlines  which 
they  have  since  retained. 

That  some  kind  -of  union  of  the  island  of  Florida  with  the 
West  Indies  took  place  in  Miocene  times  is  likewise  indicated 
by  Dr.  Matthew  f  in  his  attempt  to  delineate  the  hypothetical 
outlines  of  the  continents  in  Tertiary  times,  for  he  distinctly 
unites  southern  Florida  and  Cuba  by  land. 

According  to  Dr.  Vaughan,J  the  Florida  plateau  already 
existed  in  pre -Oligocene  times,  but  it  was  only  towards  the 
end  of  the  Oligocene  Period  that  a  portion  of  the  plateau  rose 
above  the  sea  and  apparently  remained  so  ever  since. 
Although  this  constituted  'Only  a  small  island  ("  Orange 
island  "  as  he  calls  it),  the  deposits  of  the  whole  plateau  are 
full  of  sand  and  arenaceous  material  implying  proximity  of 
land. 

From  the  opinions  cited  on  the  geological  history  of  Florida 
it  is  evident  that  there  is  nothing  distinctly  antagonistic  to 
the  view  that  part  of  the  tropical  flora  of  southern  Florida 
is  a  relict  from  Tertiary  times,  many  of  the  £pecies  being 


*  Hill,  Eobert  T.,  "Geology  of  Jamaica,"  p.  224. 

t  Matthew,  W.  D.,  "  Continents  in  Tertiary  Times,"  p.  366. 

t  Vaughan,  T.  W.,  "  Geologic  History  of  Floridian  Plateau." 


172  OKIGIN   OF   LIFE   IN   AMERICA 

probably  the  descendants  of  those  which  passed  northward 
from  the  Antilles  at  a  time  when  a  land  connection  (possibly 
in  Oligocene  times)  joined  the  latter  with  the  old  island  of 
Florida.     The  fauna  of  Florida  lends  some  support  to  this 
view.      At  any  rate,  it  gives  us  more  solid  foundations  for 
estimating    the    nature    of  the  physical  changes  which  the 
peninsula  has  undergone  within  more  recent  geological  times. 
In   the   last    chapter    I    alluded    to   a   species    of   parrot 
(Conuropsis  carolinensis)   which  in  historic  times  still  ex- 
tended its  range  as  far  north  as  the  Great  Lakes,  and  which 
seems  at  present  to  be  retreating  towards  its  original  centre 
of  dispersal  in  the  south-east.     Now  this  Carolina  parrot, 
as    it    is    generally    called,    has    no    near    relations.      Its 
closest  ally,   Conurus,   is  a  genus  of  parrot  ranging   from 
Paraguay    and    eastern    Bolivia    in    the    south    to    Mexico 
and    the    West    Indian    Islands    in    the    north.      The    fact 
of  its  occurrence  in  the  West  Indies  alone  implies  that  it  is 
an  ancient  genus,  for  these  islands  have  undoubtedly  been 
separated  from  the  continent  for  a  long  time.     Moreover, 
Cuba,  Haiti,  Mona  Island  off  Porto  Rico,  Jamaica  and  St. 
Thomas  all  possess  distinct  species  of  Conurus.    It  seems  not 
unlikely  that  Conuropsis  is  an  eastern  offshoot  of  the  older 
Conurus,  just  as  Rhynchopsittacus  has  originated  from  it  in 
the  west.    The  occurrence  of  this  parrot  on  the  mainland  does 
not  necessitate  the  former  existence  of  a  land  bridge  to  the 
West  Indies,  but,  if  other  facts  point  to  it,  the  presence  of  the 
Carolina  parrot  in  the  south-eastern  States  and  its  subsequent 
invasion  of  the  northern   States  is  more  readily  explained 
by  it. 

I  also  made  allusion  before  to  the  newt  Spelerpes,  a  genus 
confined  to  America  and  southern  Europe.  One  of  its  peculiar 
characters  is  that  its  tongue  can  be  jerked  out  to  a  considerable 
distance.  Only  one  other  newt  peculiar  to  Florida  and  Caro- 
lina, viz.,  Manculus,  agrees  with  Spelerpes  in  the  nature  of 
its  tongue,  and,  like  it,  must  be  an  ancient  genus.  Another 
very  peculiar  amphibian  is  Amphiuma  means,  an  eel -like 
creature  with  tiny  limbs,  inhabiting  the  ditches  of  rice-fields 
and  swamps  of  the  south-eastern  States.  No  fossil  remains 
of  this  interesting  species  are  known,  but  there  can  be  no 
doubt  that  it  is  a  very  old  form.  Pseudobranchus  lateralis, 


EEPTILES   OF   FLOEIDA  173 

another  most  primitive  amphibian,  is  likewise  confined  to 
the  south-eastern  States,  while  Siren  lacertina  has  its  head- 
quarters in  the  same  region.  A  very  striking  amphibian  is 
the  Florida  tree  frog  (Hyla  gratiosa),  the  largest  tree  frog  of 
North  America,  which  is  common  in  Florida,  extending  from 
there  across  the  borders  of  Georgia  and  Mississippi. 

The  most  remarkable  member  of  the  fauna  of  Florida,  from 
a  zoogeographical  point  of  view,  is  one  of  the  worm-lizards 
(Amphisbaenidae).  The  Florida  worm-lizard  (Rhinema 
floridana)  is  a  limbless,  blind,  worm-like  creature  which 
spends  its  entire  existence  under  ground.  It  is  no  doubt  of 
immense  antiquity,  and  the  only  member  of  the  family  known 
from  North  America. 

Whether  the  curious  glass -snake  (Ophisaurus  ventralis)  has 
originated  in  the  south-west  or  south-east  is  a  difficult  pro- 
blem which  future  researches  may  help  to  solve.  Professor 
Cope  *  speaks  of  an  eastern  and  western  type,  and  it  may 
possibly  have  spread  northward  from  two  independent  centres. 
I  need  scarcely  mention  that  the  glass -snake,  like  the  Euro- 
pean slow- worm,  is  a  limbless  lizard.  Anyone  may  convince 
himself  of  this  fact  by  examining  the  eyes,  which  possess 
well-developed  eyelids,  while  the  presence  of  ear  openings 
also  distinguishes  these  creatures  from  true  snakes.  The 
particular  point  of  interest  in  the  presence  of  the  glass-snake 
in  America  lies  in  the  circumstance  that  a  closely  allied 
species  (0.  apus)  inhabits  Marocco,  the  Balkan  Peninsula 
and  Asia  Minor,  while  a  second  glass -snake  is  known  from 
the  eastern  Himalayas  and  Burma.  This  extremely  discon- 
tinuous range  denotes  great  antiquity.  The  glass -snakes, 
moreover,  live  principally  underground,  and,  like  the  worm- 
lizard,  are  not  liable  to  accidental  conveyance  by  any  of  the 
occasional  means  of  dispersal  that  we  hear  so  much  of.  Their 
occurrence  on  both  sides  of  the  Atlantic  gives  great  weight 
to  the  evidence,  cited  in  previous  chapters,  of  the  former  exist- 
ence of  a  land  bridge  right  across  the  middle  of  the  Atlantic. 
I  need  not  discuss  the  subject  any  further  now,  because  it  will 
be  amply  dealt  with  in  some  of  the  succeeding  chapters,  when 
new  arrays  of  facts  in  support  of  my  contention  will  be  sub- 

*  Cope,  E.  D.,  "  Crocodilian;?,  Lizards  and  Snakes,"  p.  496. 


174  OKIGIN   OF   LIFE   IN   AMERICA 

mitted.  We  may  as  well  collect  the  facts  tending  to  support 
this  theory  as  we  proceed,  since  a  great  accumulation  of 
material  in  one  place  might  appear  wearisome. 

The  distribution  in  America  of  one  of  the  genera  of  earth- 
worms (Diplocardia),  on  which  glass-snakes  largely  live, 
somewhat  resembles  that  of  the  glass-snakes  in  America. 
There  is  a  species  in  Florida  and  three  in  Carolina.  Further 
north  the  genus  appears  in  Illinois  and  Nebraska  and  we  also 
have  a  couple  of  species  in  Mexico  and  Lower  California. 

It  was  Professor  Adams,*  I  think,  who  first  directed  atten- 
tion to  the  presence  of  two  very  distinct  and  powerful  centres 
of  dispersal,  one  in  the  south-east  and  one  in  the  south-west. 
Although  I  am  by  no  means  so  impressed,  as  Professor 
Adams  and  Dr.  Brown  are,  by  the  significance  of  the  south- 
eastern centre  of  dispersal  as  compared  with  the  south- 
western one,  which  is  incomparably  more  important,  I  quite 
concur  in  their  opinion  that  the  former  faunistic  centre  is 
perfectly  recognisable.  These  writers  moreover  discuss'  the 
problem  which  I  have  dwelt  upon  so  many  times  above,  viz., 
that  of  the  climate  during  the  Ice  Age. 

Having  adopted  the  current  views  of  the  existence  of  giant 
glaciers  in  the  northern  United  States  accompanied  by 
an  arctic  climate  Professor  Adams  f  and  Dr.  Brown  J  were 
obliged  to  search  for  suitable  "  biotic  preserves^'  where  the 
pre-Glacial  fauna  could  have  safely  weathered  the  Ice  Age. 
These  they  discovered  in  the  two  centres  of  dispersal  alluded 
to,  in  the  south-east  and  south-west,  and  from  them  they  sup- 
pose the  waves  of  migrants  to  have  streamed  forth  northward 
after  the  Glacial  Epoch  was  over.  The  presence  of  a  few 
stray  remains  of  northern  animals  south  of  their  present 
habitat  lent  a  certain  amount  of  credence  to  the  theory  in  a 
southward  extension  of  the  arctic  climate.  But  we  must 
remember  that  these  northern  creatures,  when  actually 
pressed  out  of  their  boreal  home  by  a  restriction  of 
their  habitats,  found  themselves  in  the  northern  United 


*  Adams,  C.  C.,  "  South-Eastern  States  as  a  Centre  of  Distribution,' 
p.  121. 

+  Adams,  0.  C.,  "  Post-Glacial  Dispersal  of  North  American  Biota." 
t  Brown,  A.  E.,  "  Post-Glacial  Nearctic  Centres  of  Dispersal." 


CENTRES   OF   DISPERSAL  175 

States  among  an  almost  semi-tropical  fauna  of  colossal 
sloths,  peccaries  and  other  southern  forms  that  have  long 
since  vanished,  and  which  lived  through  it  all  in  close  proxi- 
mity to  the  supposed  ice-sheets  and  arctic  climates.  The  great 
majority  of  the  Pleistocene  deposits  in  the  north  indicate  that 
the  country  had  a  milder  climate  during  the  Ice  Age  than  at 
present,  and  this  is  particularly  shown  by  those  containing 
plant  remains.  As  plants  are  supposed  to  be  more  trust- 
worthy guides  than  animals,  as  indicators  of  former  climatic 
conditions,  I  will  give  one  more  example  of  a  Pleistocene 
deposit  from  the  southern  States  which  has  come  to  my  know- 
ledge. 

A  Pleistocene  deposit  in  north  Carolina  examined  by  Pro- 
fessor Berry  *  yielded  no  boreal  or  even  cool  temperate 
plants.  Hence  it  may  safely  be  concluded,  he  thinks,  that 
the  temperature  of  the  Pleistocene  Period  in  the  same  latitude 
was  not  lower  than  it  is  now.  If  anything,  he  says,  it  was 
slightly  higher.  Additional  facts  pointing  to  the  same  general 
conclusion  are  the  former  more  northward  extension  of  the 
cypress  (Taxodium  distichum)  and  of  Planera  aquatica.  That 
these  plants  did  not  flourish  during. mild  inter-Glacial  phases 
of  the  Glacial  Epoch,  remarks  Professor  Berry,  is  indicated 
by  their  being  associated  in  Maryland  with  ice-borne  boulders 
of  considerable  size. 

To  return  once  more  to  southern  Florida,  we  find  that  what 
we  observed  among  plants,  namely,  the  tropical  element,  is 
likewise  recognisable  in  the  fauna.  According  to  Dr. 
Merriam  f  the  semi-tropical  insect  fauna  of  southern  Florida 
comprises  in  all  not  less  than  a  thousand  species  of  Antillean 
insects,  half  of  which  are  beetles. 

Among  the  mollusks  there  are  a  number  of  Antillean  genera 
represented  in  southern  Florida,  such  as  Chondropoma, 
Liguus,  Cepolis,  Varicella,  and  others  spoken  of  by  Dr. 
Pilsbry  as  Mexican  genera,  such  as  Eglandina,  Praticolella 
and  Drymaeus  (dormani  type).  Dr.  Pilsbry  regards  only  the 
last  group  as  genuine  natives  of  the  soil.  He  believes  that 
their  ancestors  entered  Florida  at  the  close  of  the  Miocene 


*  Berry,  E.  W.,  "  Pleistocene  Flora  of  Carolina,"  p.  347—348. 

t  Merriam,  C.  H.,  "  Distribution  of  Life  in  North  America,"  p.  53. 


176  ORIGIN   OF   LIFE   IN    AMERICA 

Period  by  a  land  passage,  but  does  not  state  clearly  whether 
they  came  by  a  more  direct  route  than  exists  at  present.  All 
the  other  snails  are  considered  by  Dr.  Pilsbry  *  to  be  waifs 
and  strays  derived  from  Cuba  and  the  Bahama  islands,  by  the 
agency  of  hurricanes,  drifting  trees  and  the  like. 

I  do  not  know  why  Dr.  Pilsbry  should  make  this  reserva- 
tion in  favour  of  Drymaeus,  as  one  of  the  species  found  in 
southern  Florida  (D.  dominicus)  is  also  known  from  Haiti 
and  Cuba,  besides  the  Mexican  habitat.  On  the  other  hand, 
we  must  not  forget  that  Dr.  Dall  f  discovered  a  number  of 
species  of  the  land-snails  Bulimulus  and  Cepolis  in  the 
Oligocene  Silex  beds  of  Tampa  in  Florida.  Both  of  these  have 
come  from  the  south,  for  Bulimulus,  though  extinct  in 
Florida,  still  lives  on  the  island  of  Fernando  de  Noronha  in  a 
species  almost  indistinguishable  from  one  of  the  Floridian 
ones.  Cepolis  still  inhabits  Florida,  but  is  not  found  else- 
where in  the  United  States.  It  has  its  headquarters  in  the 
West  Indies,  and  was  a  European  resident,  according  to 
Sandberger,  in  early  Tertiary  times.  Of  the  land  snail  genus 
Oxystyla,  allied  to  Drymaeus,  the  species  0.  undata  has  a  wide 
range  in  the  West  Indies,  and  is  also  known  from  southern 
Florida.  Yet  the  Floridian  specimens  both  belong  to  varieties 
peculiar  to  the  peninsula.  J  Similarly,  the  Cuban  varieties 
of  Liguus  fasciatus  are  not  the  same  as  occur  in  Florida. 

The  tropical  forms  of  mollusks  alluded  to  by  Dr.  Pilsbry 
as  inhabiting  southern  Florida  are  by  no  means  the  only  ones 
that  have  been  collected  there.  The  southern  genera 
Choanopoma,  Truncatella,  Microceramus,  Cerion  and  Veroni- 
cella  (Vaginulus)  have  also  entered  this  region.  One  of  the 
Urocoptidae  lived  in  Florida  already  in  Oligocene  times,  and 
it  is  quite  possible  that  Microceramus  pontificus  and  M.  flori- 
danus,  which  are  peculiar  to  southern  Florida,  have  existed 
there  ever  since.  Among  many  groups  of  invertebrata  long 
specific  persistence  is  much  more  common  than  is  generally 
realised.  The  fact  that  some  of  the  Floridian  species  are 


*  Pilsbry,  H.  A.,  "  Origin  of  Molluscs  of  South  Florida,"  p.  193. 
t  Dall,  W.  H.,  "  Tertiary  Fauna  of  Florida,"  Part  IV.,  p.  1565. 
|  Pilsbry,  H.  A.,  "Manual  of  Conchology  (Pulmonata),"   Vol.  XII., 
pp.  109—110. 


MOLLUSKS  OF   FLOEIDA  177 

identical  with  West  Indian  ones  does  not  necessarily  imply  a 
recent  introduction.  Some  mollusks,  at  any  rate,  seem  to  have 
preserved  their  specific  characters  unchanged  through  several 
geological  periods.  On  the  other  hand,  although  there  cannot 
be  the  slightest  doubt  that  a  certain  number  of  species  intro- 
duced by  human  agency  thrive  in  other  localities  besides  their 
native  homes,  I  am  not  convinced  that  mollusks  spread  across 
any  wide  expanse  of  sea  by  other  accidental  transport.  With 
Mr.  Bryant  Walker  *  I  prefer  to  attribute  the  tropical  land 
mollusks  of  Florida  largely  to  a  former  land  connection 
between  the  then  island  of  Florida  and  a  larger  southern  land- 
mass.  I  cannot,  however,  agree  with  Mr.  Walker's  view  that 
this  event  took  place  in  comparatively  recent  times.  Dr. 
Simpson  urges  that  the  Floridian  area  must  have  been  joined 
to  the  greater  Antilles  by  way  of  the  Bahamas  in  Eocene 
times.  Nevertheless,  he  does  not  derive  the  tropical  species 
of  Florida  from  the  southern  invasion  which  must  have  taken 
place  at  that  time.  He  favours  a  recent  colonisation  by  acci- 
dental transport.  The  rich  fauna,  of  the  Bahama  islands  seems 
to  him  entirely  derived  from  the  greater  Antilles  in  that 
manner. f 

There  are  certain  geological  grounds  for  the  supposition 
that  an  ancient  Archaean  land-mass  trending  north-eastward 
from  the  northern  end  of  the  Andes  once  existed,  and  that 
traces  of  it  are  still  recognisable  in  Guatemala,  Cuba  and 
Haiti.  J  Much  of  this  early  land  may  still  have  stood  above 
sea-level  in  early,  and  perhaps  middle,  Tertiary  times,  form- 
ing a  centre  from  which  the  North  American  continent  de- 
rived part  of  its  present  fauna. 

Dr.  Ortmann  §  demonstrated  in  a  very  convincing  manner 
that  the  fresh-water  crayfish  belonging  to  the  genus  Cambarus 
originated  in  Mexico,  spreading  from  this  centre  of  dispersal 
into  the  United  States  at  the  beginning  of  the  Tertiary  Era. 
The  centres  for  the  more  advanced  forms  of  the  sub-genus 
Cambarus,  and  for  the  sub-genera  Faxonius  and  Bartonius, 

*  Walker,  Bryant,  "  Origin  of  American  Mollusca,"  p.  56. 
t  Simpson,  C.  J.,  "  Land  and  Freshwater  Mollusks  of  West  Indian 
Eegion,"  pp.  447—448. 

t  Frazer,  T.,  "History  of  Caribbean  Islands,"  p.  398. 

§  Ortmann,  A.  E.,  "  Affinities  of  Cambarus,"  pp.  124—125." 

L.A.  N 


178  OKIGIN   OF   LIFE   IN   AMEEICA 

are  situated  in  the  southern  States  of  North  America.  It  is 
suggested  by  Dr.  Ortmann  that  the  south-eastern  centre  of 
the  early  forms  of  Cambarus  originated  from  the  more  ancient 
south-western  one  by;  a  process  of  migration  across  the  present 
continent.  May  not  these  early  forms  have  travelled  eastward 
from  Mexico  towards  Cuba  and  Florida  when  the  latter  were 
connected  directly  by  land  with  Central  America  ?  A  species 
of  Cambarus  still  lives  in  the  rivers  of  Cuba. 

Instead  of  mollusks  or  crayfish  we  may  take  almost  any 
group  of  North  American  invertebrates  and  readily  discover 
among  them  certain  ancient  forms,  which  are  either  confined 
to  small  areas  in  the  south-eastern  States  or  have  evidently 
spread  northward  from  a  south-eastern  centre. 

Scorpions,  for  instance,  are  universally  acknowledged  to  be 
a  very  ancient  group.  The  genus  Centrurus  has  its  head- 
quarters in  the  West  Indies  and  Central  America.  Now 
four  species  of  Centrurus  are  known  from  Florida,  viz.,  C. 
gracilis,  C.  carolinianus,  C.  margaritatus  and  C.  hentzi,  the 
latter  being  peculiar  to  Florida.  The  allied  genus  Tityus, 
which  is  rather  more  southern  in  distribution  than  Centrurus, 
has  one  endemic  species  in  Florida,  viz.,  T.  floridanus.* 
Altogether  the  southern  part  of  Florida  shows  marked  affini- 
ties with  the  West  Indies.  There  are  also  some  species  in 
Florida  such  as  Cupiennius  sallei,  Keys,  not  yet  recorded  from 
the  Antilles,  which  are  known  from  Central  America.  Quite  a 
similar  southern  relationship  has  been  noticed  among  many  of 
the  Floridian  Orthopteraf  and  the  Coleoptera.j:  One  of 
the  most  noteworthy  genera  of  beetles  recorded  from  Florida 
is  Khopalomesites.  It  has  spread  northward  as  far  as  Dela- 
ware, and  reappears  across  the  Atlantic  in  western  and 
southern  Europe. 

As  regards  the  dragon-flies  and  their  allies  (Neuroptera),  a 
few  species  are  common  to  the  West  Indies  and  the  northern 
continent.  Some  of  these  may  have  flown,  or  have  been  con- 
veyed by  a  storm,  from  one  region  to  the  other.  Such  a  method 
of  colonisation,  however,  cannot  Jiave  been  usedj  by  Enallagma, 

*  Banks,  Nathan,  "  Arachnida  of  Florida,"  p.  142. 

t  Kehn,  J.  A.,  and  M.  Hebard,  "  Orthoptera  of  Florida." 

J  Schwarz,  E,  A.,  "  Coleoptera  of  Florida." 


SCOKPIONS   AND  DRAGON-FLIES  179 

according  to  Prof.  Kolbe,*  on  account  of  its  feeble  development 
and  weak  flight.  Taking  into  consideration  the  general  dis- 
tribution of  ^this  genus,  he  favours  the  view  of  a  former 
ancient  land  connection  between  the  Antilles  and  North 
America. 

In  its  butterflies  and  moths  Florida  is  united  to  Central 
America  and  the  Antilles,  and  it  is  from  the  latter  that  such 
genera  as  Heliconius,  Dione  and  Agraulis  gained  a  foothold  in 
the  northern  continent.f 

An  exceedingly  ancient  group  are  the  woodlice  (Isopoda)  or 
"  sowbugs  "  as  they  are  sometimes  called  in  America.  In 
eastern  Europe  at  Odessa,  and  again  in  north-western  Africa, 
an  interesting  very  peculiar  species  occurs  which  is  known 
as  Tylos  latreilli.  The  same  species  has  been,  met  with  in 
southern  Florida  and  in  the  Bermuda  islands.  A  case  of  that 
kind  is  generally  set  down  at  once  as  an  instance  of  human 
importation.  The  possibility  of  the  survival  of  such  a  species 
through  several  geological  ages  is  not  even  discussed.  But 
in  southern  Florida  a  second  species  of  Tylos  has  been  dis- 
covered which  occurs  elsewhere  only  in  Bermuda.  This 
species,  known  as  Tylos  niveus,  is  white  in  colour  and  pos- 
sesses structural  differences  distinguishing  it  from  the  other. 
Of  the  genus  Cubaris,  which  is  widely  distributed  through  the 
Antilles  sand  westward  to  Mexico  and  California,  a  single 
species  (Cubaris  pisum)  occurs  in  Florida,  and  is  peculiar 
to  it.f 

All  these,  it  may  bp  objected  to,  are  inconspicuous  creatures 
that  might  have  been  overlooked  elsewhere.  Too  much  im- 
portance, it  might  be  urged,  should  not  be  placed  on  their 
occurrence  in  Florida.  We  may  return,  therefore,  to  more 
conspicuous  objects. 

Everyone  in  America  knows,  or  has  heard  of,  the  alli- 
gator (Alligator  mississippiensis),  though  it  is  only  found 
in  the  southern  states  of  North  America.  Its  distribu- 
tion in  fact  is  rather  limited.  From  Florida  it  extends 
northward  to  Carolina  and  westward  as  far  as  tlie  Eio 


*  Kolbe,  H.  J.,  "  Neuroptera  der  Antillen,"  pp.  157—158. 

t  Pagenstecher,  A.,  "  Verbreitung  der  Schmetterlinge,"  p.  359. 

\  Eichardson,  H.,  "  Isopods  of  North  America." 

N2 


180  ORIGIN   OF   LIFE   IN   AMERICA 

Grande.  Only  one  other  species  of  alligator  is  known,  viz., 
Alligator  sinensis  from  the  Yangtse  River  in  China.*  This 
enormously  discontinuous  range  is  significant,  and  implies 
great  antiquity.  Fortunately  we  possess  most  valuable 
palaeontologies!  evidence  as  to  the  alligator's  antecedents. 
Even  the  most  pronounced  advocate  of  accidental  dispersal 
would  not  venture  to  apply  the  usual  methods  of  wind,  waves 
or  hurricanes  to  explain  the  origin  of  this  example  of  dis- 
tribution. The  generally  accepted  theory,  I  believe,  is  that 
some  ancestor  of  the  American  alligator  has  travelled  north- 
ward, and  succeeded  in  crossing  the  former  land  bridge  across 
Bering  Strait  to  north-eastern  Asia,  thence  wandering  south- 
ward to  China.  We  possess  no  fossil  evidence  for  such  a 
belief.  All  we  know  is  that  the  rather  generalised  alligator 
Diplocynodon  lived  already  at  the  very  commencement 
of  the  Tertiary  Era  both  in  North  America  and  in  Europe, 
and  that  it  persisted  in  Europe  until  Miocene  times.  Henoe 
it  seems  likely  that  the  modern  genus  Alligator  originated  in 
early  Tertiary  times  either  in  Europe  or  North  America,  and 
spread  thence  to  Asia.  That  America  was  probably  the  centre 
of  dispersal  is  indicated  by  certain  characters  the  Chinese 
alligator  has  in  common  with  the  South  American  caimans. 

An  equally  remarkable  fact  of  distribution  is  that  the  true 
crocodile  has  succeeded  in  obtaining  a  footing  on  the  North 
American  continent  in  one  single  small  area,  namely,  in  that 
in  which  I  have  already  signalled  so  many  tropical  speciee, 
in  southern  Florida.  We  are  apt  to  associate  crocodiles  with 
Africa.  Yet  they  have  a  much  wider  distribution.  The  genus 
Crocodilus  occurs  in  Africa,  Syria,  India  and  eastward  as  far 
as  northern  Australia.  Westward  it  reappears  in  South 
America,  the  West  Indies  and  Central  America.  The  species 
alluded  to  (Crocodilus  americanus)  is  the  only  member  of  the 
family  inhabiting  the  West  Indian  islands,  and  it  also  occurs 
in  Central  America,  Columbia,  Ecuador  and  Venezuela. 
Remains  of  crocodiles  found  in  the  Eocene  of  Wyoming 
and  the  eastern  States  have  been  referred  by  Leidy,  Cope 
and  others  to  the  genus  Crocodilus.  The  presence  of  croco- 
diles in  America  dates  back,  then,  to  the  very  beginning  of 
the  Tertiary  Era,  and  it  seems  surprising  that  they  have  not 

*  Barbour,  Th.,  "  Chinese  Alligator." 


ALLIGATOKS   AND   CROCODILES  181 

spread  more  widely  in  America.  Although  the  American 
crocodile  is  fond  of  salt  marshes,  and  some  of  the  eastern 
crocodiles  actually  frequent  the  sea  coast,  I  cannot  for  a 
moment  believe  in  the  possibility  of  a  crocodile  crossing  an 
ocean  such  as  the  Atlantic.  Only  a  land  connection  between 
America  and  the  Old  World  in  early  Tertiary  times  can 
explain  its  present  geographical  distribution. 

Of  West  Indian  mammals  none  have  so  far  been  observed  in 
Florida,  unless  we  include  the  raccoons  among  them.  It  is  a 
most  remarkable  fact  that  a  raccoon  (Procyon  maynardi) 
inhabits  New  Providence,  one  of  the  Bahama  islands.  At 
the  first  impulse  we  might  think  of  a  chance  introduction  by 
floating  trees  from  the  mainland  of  Florida.  But  Florida  lies 
one  hundred  and  seventy  miles  west  of  New  Providence,  and  is 
separated  from  it  by  a  swift  current  flowing  northward. 
Raccoons  occur  nowhere  else  in  the  West  Indian  islands, 
and  the  New  Providence  species  differs  from  that  of  the  main- 
land. In  the  last  chapter  (p.  151)  I  contended  that  the 
whole  family  Procyonidae  was  certainly  of  American  origin, 
and  I  thought  the  genus  Procyon  might  have  arisen  in  Plio- 
cene times.  Possibly  it  is  much  older,  though  we  possess  no 
palaeontological  evidence  in  support  of  such  a  supposition.  If 
the  Bahama  islands  had  still  been  joined  to  Florida  when  the 
latter  had  already  become  a  peninsula  of  North  America,  we 
should  expect  a  good  many  of  the  smaller  mammals  to  have 
crossed  over  to  the  Bahamas,  which  they  have  not  done.  So 
far,  the  occurrence  of  this  species  of  raccoon  in  the  Bahamas 
is  a  complete  puzzle  to  me. 

Before  concluding  this  brief  survey  of  the  south-eastern 
fauna  I  should  like  to  dispel  the  impression  I  may  have  given 
that  the  tropical  element  forms  any  great  share  in  the  verte- 
brate fauna  of  Florida.  On  the  contrary,  the  majority  of  the 
genera  and  species  undoubtedly  poured  into  the  peninsula 
from  the  north  and  north-west,  and  they  appear  to  be  gradu- 
ally displacing  the  southern  element.  At  any  rate,.  I  look  upon 
the  latter  as  a  relict  of  the  Tertiary  Era. 

There  are  many  species  of  mammals  peculiar  to  Florida, 
but  not  so  many  as  we  might  expect  from  the  favourable 
climatic  conditions  of  the  country.  On  the  whole,  the 
mammalian  fauna  of  the  peninsula  bears  the  impress  of  a 


182  ORIGIN   OF   LIFE   IN   AMERICA 

newly  emerged  land  which  has  been  populated  from  the  north 
within  recent  geological  times.  The  most  noteworthy  species 
that  might  be  mentioned  is  the  Florida  water  vole  (Microtus 
alleni) .  It  is  not  alone  the  only  North  American  water  vole, 
but  also  the  sole  member  of  the  sub-genus  Neofiber,  and  thus 
forms  a  connecting  link  between  the  genera  Microtus  and 
Fiber,  that  is  to  say,  between  the  meadow  voles  and  the 
musk  rats.* 

I  have  endeavoured  to  describe  in  almost  every  chapter  the 
range  of  some  typically  'North  American  mammal.  Some  have 
not  yet  been  alluded  to,  among  them  the  opossum.  Two 
species  are  now  often  distinguished  in  North.  America,f  one  of 
which  is  supposed  to  extend  its  range  into  South  America.  As 
a  matter  of  fact  the  northern  <and  southern  forms  are 
extremely  difficult  to  discriminate  from  one  another,  and 
many  authorities  are  of  opinion  that  they  merely  represent 
varieties  of  one  species  (Didelphys  marsupialis)  which  thus 
has  an  enormously  extensive  distribution  in  North  and  South 
America. 

The  existing  marsupials,  or  pouched  animals  as  we  may  call 
them,  are  generally  regarded  as  modern  survivors  of  one  of  the 
ancient  groups  of  mammals,  which  apparently  spread  almost 
all  over  the  globe  before  the  superior  beasts  of  more  recent 
times  had  made  their  appearance.  It  is  believed  that  at  the 
time  of  their  prime,  Australia  became  separated  from  the 
mainland  of  Asia,  so  that  this  southern  continent  now  forms 
the  headquarters  of  the  group,  while  in  other  parts  of  the 
world  they  succumbed  in  the  struggle  with  superior  and  better 
fitted  animals.  Yet  in  America,  where  competition  with  the 
more  highly  developed  and  more  aggressive  beasts  ought  to 
be  very  keen,  opossums,  which  belong  to  the  marsupials, 
are  by  no  means  on  the  verge  of  extinction.  On  the 
contrary,  they  hold  their  own  perfectly  against  the  more 
modern  competitors.  The  genus  Didelphys  is  much  more 
abundantly  represented  in  South  America  than  on  the 
northern  continent,  and  other  genera  of  marsupials  occur 
there  besides  opossums.  To  judge  from  these  modern  repre- 

*  Bangs,  Outram,  "  Mammals  of  Florida  and  Coast  Eegion." 
+  Allen,  J.  A.,  "  North  American  Opossums." 


THE   ISLAND   OF   BEKMUDA  183 

sentatives  of  the  marsupials,  it  would  not  be  unreasonable  to 
argue  that  the  opossums  had  invaded  North  America  from  the 
southern  continent.  Mr.  Lydekker's  *  conclusion  is  that 
opossums  are  only  recent  immigrants  from  the  south, 
although  he  does  not  believe  that  South  America  was  their 
original  home.  He  (p.  55)  selects  south-eastern  Asia  as  the 
birthplace  of  the  opossum  family  (Didelphyidae),  urging  that 
the  latter  scattered  'from  this  .centre  towards  Europe  and  North 
America.  He  also  contends  that  the  allied  family  Dasyu- 
ridae  (Originated  in  southern  Asia,  spreading  thence  to 
Australia,  and  by  an  antarctic  land  connection  from  there  to 
South  America.  I  shall  return  to  this  subject  in  somo  of  the 
subsequent  chapters  (p.  283  and  p.  366). 

There  is  still  another  problem  of  exceptional  interest  which 
I  wish  to  enlarge  upon,  namely,  that  of  the  origin  of  the 
Bermudan  fauna.  The  island  of  Bermuda  has  certain 
faunistic  affinities  with  Florida,  and  we  may  therefore  con- 
sider the  origin  of  its  fauna  as  an  appendix  to  this  chapter. 
It  consists  in  reality  of  a  series  of  about  one  hundred 
islands  and  islets,  their  total  area  being  less  than  twenty 
square  miles.  The  island  of  Bermuda,  as  we  may  call  it  for 
the  sake  of  brevity,  lies  approximately  seven  hundred  miles 
eastward  of  North  Carolina,  being  apparently  surrounded  on 
all  sides  by  a  depth  of  from  1,500  to  2,000  fathoms. 
Dr.  Wallace,f  who  gives  us  a  brief  description  of  the 
fauna  and  flora  of  the  island,  concludes  that  Bermuda 
furnishes  us  with  one  of  the  most  instructive  facts  as  to  the 
power  of  many  groups  of  organisms  to  pass  over  seven 
hundred  miles  .of  open  sea.  There  is  no  doubt  whatever, 
he  remarks,  that  all  the  indigenous  species  have  thus  reached 
the  island. 

I  may  as  well  say  that  my  own  views  differ  entirely  from 
those  of  Dr.  Wallace  as  regards  the  origin  of  Bermuda  and  of 
its  indigenous  fauna  and  flora.  I  believe  the  island  to  have 
formed  part  of  a  wide  belt  of  land,  which  extended  northward 
from  the  West  Indies,  joining  the  mainland  of  North  America 
somewhere  near  Massachusetts,  at  a  time  when  most  of  the 

*  Lydekker,  E.,  "  Geographical  History  of  Mammals,"  p.  108. 
t  Wallace,  A.  E.,  "Island  Life,"  p.  2713. 


184  ORIGIN   OF   LIFE   IN   AMERICA 

existing  coast  line  of  the  Atlantic  States  south  of  Massachu- 
setts was  submerged  (Fig.  14).  I  look  upon  the  indigenous 
animals  and  plants  of  Bermuda  as  relicts  of  an  ancient  fauna 
and  flora.  I  hold,  moreover,  that  Bermuda  furnishes  us  with 
one  of  the  most  instructive  facts  of  the  exceedingly  slow 
change  that  many  species  of  animals  and  plants  undergo 
through  successive  geological  ages,  and  that  it  does  not  sup- 
port the  theory  advocated  by  Dr.  Wallace  that  many  organisms' 
possess  the  power  of  crossing  seven  hundred  miles  of  open 
sea. 

The  geology  of  Bermuda,  so  far  as  the  visible  structure  is 
concerned,  is  identical  with  that  of  the  Bahamas,  except  that 
the  coral  reefs  are  of  greater  importance  in  the  latter.  The 
rocks  in  both  are  limestone,  and  red  clays  resulting  from  its 
decomposition.  Nearly  all  the  rocks  of  Bermuda  above 
sea-level,  and  to  a  considerable  depth  below  it,  are  made  up  of 
wind-drifted  shell  sand  with  very  little  material  derived  from 
corals  and  other  organisms.  These  materials,  according  to 
Professor  Verrill,  when  consolidated,  form  a  true  aeolian  lime- 
stone. The  island  is  surrounded  by  coral  reefs  in  such  a 
manner  as  to  give  it  the  appearance  of  an  atoll  of  the  Pacific 
Ocean.  It  was  actually  regarded  as  such  by  Professor  Rice.* 

The  greater  Bermuda  or  "  Pliocene  Bermuda  "  as  it  has 
been  called,  which  was  once  dry  land,  had  an  area  of  about  two 
hundred  and  thirty  square  miles.  That  this  greater  Bermuda 
represents  an  older  land  surface  was  revealed  during  the  exca- 
vations made  in  1870  for  harbour  worts.  These  extended  to 
over  fifty  feet  below  sea-water  level.  At  a  depth  of  forty- 
six  feet,  as  Mr.  Jones  f  tells  us,  a  stratum  of  peat  and  red 
earth  two  feet  thick  was  found,  containing  the  vertical  stumps 
of  cedar  trees.  This  again  rested  on  hard  aeolian  limestone, 
containing  fossil  land  shells  of  the  genus  Poecilozonites. 
There  is  clear  evidence,  therefore,  of  a  subsidence  of  the 
land  to  the  extent  of  at  least  fifty  feet.  A  re-elevation  to 
that  extent  would  nearly  restore  the  island  of  greater 
Bermuda.  Beyond  this,  in  a  south-westward  direction,  several 
shallows  have  been  detected,  all  being  surrounded  by  great 

*  Eice,  W.  N.,  "Geology  of  Bermuda,"  p.  9. 

t  Jones,  J.  M.,  "Recent  Observations  in  Bermudas,"  p.  262. 


GEOLOGY   OF   BEKMUDA  185 

depths,  yet  indicating  that  they  represent  a  range  of  drowned 
mountains. 

According  to  Professor  Verrill  it  is  now  generally  admitted 
that  Bermuda  is  the  flattened  and  greatly  eroded  summit  of  a 
vast  submarine  volcano,  and  he  thinks  it  most  reasonable  to 
suppose  that  its  last  activity  corresponded  in  time  with  the 
last  great  volcanic  eruptions  of  the  nearest  American  main- 
land. This,  as  he  remarks,  would  imply  that  the  Bermuda 
volcano  was  formed  or  completed  during  the  Triassic  Period 
or  at  its  close.  Immense  outbursts  of  volcanic  material  took 
place  all  along  the  eastern  coast  of  America  at  that  time, 
giving  rise  to  enormous  trap-dykes.  In  Nova  Scotia  these 
dykes  have  a  nearly  north  and  south  direction,  and  they  may 
have  had  some  direct  relation  with  the  volcano  of  Bermuda. 
It  is  estimated  that  the  latter  had  a  height  of  about  15,000  feet.* 

The  whole  surface  structure  of  Bermuda  reminds  us  vividly 
of  the  Bahamas.  The  latter  owe  their  configuration  to  the 
same  process  of  waste  which  has  been  going  on  during  their 
subsidence.  The  coral  reefs  surrounding  the  Bahamas  form 
but  an  insignificant  part  of  the  topography  of  the  islands. 
The  same  aeolian  rocks  as  in  Bermuda  cover  all  the  visible 
parts  of  the  Bahamas,  and  we  find  an  intercalation  of  similar 
red  earth.  Altogether  there  is,  as  Professor  Agassiz  points 
out,  clear  evidence  of  the  comparatively  recent  subsidence 
of  at  least  three  hundred  feet  of  the  Bahama  Bank.j- 

A  slightly  greater  elevation  would  have  had  the  effect  of 
shutting  out  the  Gulf  Stream  from  the  northern  Atlantic, 
for  it  now  pursues  its  swift  northern  course  through  the 
shallow  channel  lying  between  the  Bahama  Bank  and  Florida. 
Now  it  is  interesting  to  note  that  the  ancestral  Gulf  Stream 
did  not  flow  where  it  does  now,  but  across  northern  Florida, 
thus  separating  the  northern  from  the  southern  portion  of  the 
peninsula.  Not  only  were  northern  Florida  and  Georgia  sub- 
merged. Tertiary  marine  deposits  are  known  even  as  far  north 
as  New  Jersey.  The  sea  covered  a  vast  area  of  the  present 
southern  Atlantic  States.  That  a  strong  current  flowed 
through  the  channel  of  north  Florida  is  evidenced  by  the  fact 

*  Verrill,  A.  E.,  "Bermuda  Islands— Geology,"  XII.,  pp.  47—82. 
t  Agassiz,  A.,  "  Reconnaissance  of  Bahamas,"  p.  7. 


186  ORIGIN   OF   LIFE   IN   AMERICA 

that  during  early  Tertiary  times  Antillean  species  were  carried 
even  as  far  as  New  Jersey.  At  no  succeeding  Epoch,  says  Dr. 
Dall,  do  we  find  such  tropical  and  semi-tropical  molluaks 
extending  northward  to  such  a  distance  from  their  present 
range.  All  these  Tertiary  deposits  cease  north  of  the  Hudson 
estuary,  and  I  have  shown  in  ,a  previous  chapter  (p.  41) 
that  in  later  Tertiary  times,  at  any  rate,  the  coasts  of  New 
Yor"k,  Massachusetts  and  Maine  extended  far  out  into  the 
present  Atlantic.  The  hypothesis  of  the  latter  land  extension 
having  once  joined  Bermuda  and  the  Bahamas,  etc.,  seems  to 
me  supported  by  a  variety  of  circumstances  which  I  shall 
allude  to  later  on.  This  would  have  excluded  the  Atlantic 
Ocean  either  partially  or  wholly  from  the  Gulf  of  Mexico  and 
the  southern  Atlantic  States.  Some  time  during  the  Miocene 
Period,  or  earlier,  a  sudden  influx  of  northern  species  into  the 
area  hitherto  occupied  by  southern  forms  occurred.  Dr.  Dall 
and  Mr.  Harris  *  endeavoured  to  account  for  this  phenomenon 
by  the  supposition  that  the  course  of  the  Gulf  Stream  was 
gradually  turned  more  off  shore  than  it  was  before  or  is  at 
present. 

If  we  assume,  however,  that  a  belt  of  land  such  as  above 
described  had  hitherto  existed,  the  gradual  breaking  down  of 
its  northern  portion  might  have  admitted  the  Atlantic  waters 
into  the  sea  which  covered  the  southern  States  and  have 
brought  with  it  the  new  fauna,  which  had  meanwhile  deve- 
loped in  the  northern  Atlantic  Ocean  (see  Figs.  14  and  16). 
For  a  time  these  northern,  cooler  inshore  waters  were  even 
able  to  penetrate  into  the  Gulf  of  Mexico.  Even  if  we  grant 
the  correctness  of  Messrs.  Dall  and  Harris's  supposition  of  the 
altered  course  of  the  Gulf  Stream,  the  cause  of  this  deflection 
is  more  likely  to  have  been  produced  by  a  change  in  the  con- 
figuration of  the  northern  land-masses  than  by  that  of  Florida. 

Let  us  now  study  the  flora  and  fauna  of  Bermuda,  and 
endeavour  to  ascertain  whether  it  supports  in  any  way  the 
theory  I  have  advocated. f  It  is  quite  evident  that  the  existing 
flora  of  Bermuda  is  only  a  remnant  of  the  original  one,  before 
the  early  settlers,  accompanied  by  hogs  and  rats,  played  havoc 

*  Dall,  W.  H.,  and  G.  D.  Harris,   "Correlation  Papers,"  pp.  185—187. 
t  Heilprin,  A.,  "  The  Bermuda  Islands." 


FLORA   OF   BERMUDA  187 

with  it.  The  old  records  speak  of  thousands  of  palmetto  trees 
that  were  cut  down,  and  of  cedars  used  for  the  construction 
of  ships  and  buildings.  The  palmetto  (Sabal  blackburniana) 
is  a  species  of  palm  much  like  that  of  southern  Florida,  but 
differing  sufficiently  to  form  a  distinct  species.  All  the  islands 
were  once  thickly  covered  with  the  cedar  (Juniperus  bermu- 
diana),  and  it  also  occurs  in  a  semi-fossil  condition  in  the 
red  earth.  Among  the  one  hundred  and  fifty  six  kinds  of  land 
plants  now  considered  native  to  Bermuda,  about  fifty  species 
are  very  restricted  in  their  distribution,  most  of  them  being  of 
West  Indian  origin.  Altogether  one  hundred  and  eighteen 
species  are  native  of  the  West  Indies.  Of  these  ninety  are 
also  found  in  Florida,  the  remainder  being  only  met  with  in 
the  West  Indies.  About  the  same  number  of  plants  as  are 
common  to  Bermuda  and  the  West  Indies  only,  are  also 
peculiar  to  Bermuda  and  continental  North  America.  A  few, 
such  as  the  blue-eyed  grass  (Sisyrinchium  bermudianum), 
have  their  nearest  relatives  in  the  north.- eastern  States.  Most 
of  the  botanists  who  have  investigated  the  Bermuda  flora, 
especially  Mr.  Hemsley,  Mr.  Moseley  and  more  recently  Pro- 
fessor S.  Brown,  Dr.  Harshberger  and  Prof essor  Yerrill  *  are 
agreed  that  all  the  native  plants  of  the  island  have  been  intro- 
duced by  natural  agencies  prior  to  the  advent  of  man.  Pro- 
fessor Verrill  is  of  opinion,  and  I  feel  sure  his  view  is 
almost  generally  accepted,  that  migratory  birds  have  prob- 
ably always  been  the  chief  agencies  for  these  introductions 
of  plants,  especially  those  from  north-eastern  North  America. 
Currents,  floating  timber  and  hurricanes  are  also  supposed 
to  have  had  their  share  in  transporting  plants  from  various 
parts  of  America  to  Bermuda.  I  am  among  rthe  few.  who  do  not 
recognise  the  potency  of  these  agencies  of  transport.  That 
seeds  are  occasionally  cast  by  currents  upon  the  shores  of 
lonely  islands  like  Bermuda  has  been  amply  proved,  but  there 
is  no  evidence  available  to  show  that  migratory  birds  distribute 
seeds  on  siuch  islands,  or  that  hurricanes  carry  seeds  across 
seven  hundred  miles  of  sea  and  safely  deposit  them  on  an 
island.  These  theories  are  very  widely  accepted,  but  I  think 
on  insufficient  grounds. 

*  Verrill,  A.  E.,  "Bermuda  Islands,"  XI.,  pp.  587—588. 


188  OBIGIN   OF   LIFE   IN   AMERICA 

Dr.  Wallace  *  makes  the  statement  that  the  few  species  of 
birds  which  are  resident  in  Bermuda  and  breed  on  the  island 
are  so  constantly  crossed  by  individual  migrants  of  the  same 
species  from  the  mainland  that  none  of  the  former  have 
acquired  any  .special  peculiarity  constituting  even  a  distinct 
variety.  It  is  perfectly  true  that  the  resident  land  birds 
are  very  few  in  number,  but  the  opinions,  of  most  recent  autho- 
rities differ  very  considerably  from  those  enunciated  by  Dr. 
Wallace. 

Only  ten  species  of  land  birds  are  resident  on  the  island, 
and  three  of  these  have  been  introduced  by  man.  The  indi- 
genous fauna  includes,  therefore,  seven  "kinds  of  birds, 
namely,  the  ground  dove,  the  Florida  gallinule,  the  crow,  the 
white-eyed  Vireo,  the  blue  bird,  the  cat  bird  and  the  cardinal. 

Of  these  the  Bermuda  ground  dove  (Columbigallina  bermu- 
diana)  is  described  as  a  species  very  distinct  from  the 
American  C.  passerina.  The  Florida  gallinule  (Gallinula 
galeata)  does  not  seem  to  differ  from  the  continental  form. 
The  crow  of  Bermuda  is  probably  separable  from  the  American 
crow,  but  has  not  been  sufficiently  studied.  The  white-eyed 
Vireo  (Vireo  bermudianus)  is  described  by  Messrs.  Bangs 
and  Bradlee  as  very  different  in  all  its  ways  from  its  shy, 
retiring,  continental  relative,  V.  noveboracensis.f  The  blue 
bird  is  not  usually  recognised  as  distinct  from  the  continental 
form,  but  Dr.  Sharpe  of  the  British  Museum  held  that  its 
characters  were  certainly  striking  enough  to  deserve  specific 
recognition,  and  he  described  it  as  Sialis  bermudianus.  Now  I 
may  mention  that  the  blue  bird  belongs  to  one  of  those  genera 
which  seem  to  have  retained  their  generic  characters  for  very 
long  ages  past,  probably  throughout  several  geological  periods. 
We  know  nothing  of  its  past  history  from  palaeontological  evi- 
dence, but  its  present  geographical  distribution,  and  that  of- 
its  nearest  relative,  are  so  peculiar  as  to  suggest  their  being  of 
great  antiquity.  Sialis,  with  its  three  closely-allied  American 
species,  has  its  nearest  relative  (Grandala)  in  the  Himalayan 
Mountains.  I  only  mention  this  fact  so  as  to  show  that  the 
apparent  specific  identity  of  the  Bermudan  and  the  continental 

*  Wallace,  A.  E.,  "  Island  Life,"  p.  269. 

t  Bangs,  0.,  and  T.  S.  Bradlee,  "  Birds  of  Bermuda,"  pp.  249—257. 


BIRDS   OF   BERMUDA  189 

blue  bird  need  not  necessarily  be  adduced  as  an  argument 
for  the  recent  geological  origin  of  the  former.  "The  Bermuda 
catbird  (Galeoscoptes  bermudianus),  though  closely  resem- 
bling the  continental  species,  is  considered  distinct  by  Messrs. 
Bangs  and  Bradlee  and  by  Dr.  Sharpe.  Finally,  the  Bermuda 
cardinal  (Cardinalis  bermudianus)  can  at  once  be  identified 
from  its  continental  relative  by  its  characteristic  bill. 

Dr.  Wallace  alludes  to  the  Bermudan  lizard  as  being  the 
only  vertebrate  animal  which  exhibits  any  peculiarity.  But 
much  more  can  be  said  about  it.  It  is  a  member  of  the  family 
of  ,skinks  (Scincidae),  which  is  of  cosmopolitan  range  and 
undoubtedly  of  great  age.  The  Bermudan  skink  (Eumeces 
longirostris)  is  said  to  be  nearly  related  to  the  American  blue  • 
tailed  lizard  (Eumeces  quinquelineatuts),  still  we  must  remem- 
ber that  the  latter  has  long  been  considered  identical  with  the 
Japanese  skink  (Eumeces  latiscutatus)  from  which  it  can 
be  separated  only  by  very  careful  study.*  It  may  safely  be 
argued,  therefore,  that  the  Bermudan  skink  has  originated  in 
early  Tertiary  times  (compare  pp.  123 — 126). 

Dr.  Rehn  f  records  twenty-eight  species  of  Orthoptera,  two 
of  them,  viz.,  Paroxya  bermudensis  and  Gryllus  bermudensis, 
being  peculiar  to  the  island.  If  we  exclude  the  cosmopolitan 
and  circumtropical  forms  which  the  author  regards  as  prob- 
ably introduced  by  commerce,  the  remainder  are  more  closely 
related  to  continental  than  to  Antillean  species. 

Only  a  single  ant  is  peculiar  to  Bermuda,  viz.,  Prenolepis 
kincaidi,  because  some  of  the  more  active  recently  introduced 
warlike  species  have  no  doubt  exterminated  the  greater  part 
of  the  older  resident  ant  fauna.  J 

Mr.  Pocock  §  recognised  two  species  of  myriopods  from 
Bermuda  as  doubtfully  distinct,  though  he  described  them  as 
new  species.  These  are  Lithobius  provocator  and  Lithobius 
bermudensis.  Altogether  he  believes  that  only  six  species 
of  centipedes  ,and  millipedes  are  native  to  Bermuda,  and  that 
three  of  them  belong  unquestionably  to  the  Mediterranean 

*  Garman,  Sam,  "  Eeptiles  of  Bermuda,"  p.  287. 
t  Behn,  J.  A.  GK,  "  Orthoptera  of  Bermuda,"  p.  3. 
%  Wheeler,  W.  M.,  "Ants  of  Bermuda,"  p.  347. 

§  Pocock,  E.  L,  "  Myriopoda  of  the  Challenger  Expedition,"  pp.  123— 
124. 


190  OKIGIN   OF   LIFE   IN   AMERICA 

fauna.  This  is  a  point  of  considerable  interest  and  import- 
ance, and  requires  to  be  more  closely  studied  in  a  recon.- 
sideration  of  the  true  relationship  of  the  members  of  other 
groups  of  invertebrates. 

This  relationship  is  clearly  recognisable  among  the  ter- 
restrial Isopods  or  wood-lice,  which  have  been  described 
by  Miss  Eichardson.  Tylos  latreilli,  as  already  quoted, 
is  a  typical  Mediterranean  species,  which  has  been  dis- 
covered in  southern  Florida,  where  also  another  species, 
Tylos  niveus,  occurs.  Both  of  these  are  now  recorded  from 
Bermuda.  The  European  genus  Porcellio  is  represented  by 
two  species,  one  of  them  (Porcellio  parvicornis)  new  to 
science.  Metoponorthus  sexfasciatus,  a  typically  Mediter- 
ranean species,  also  found  in  the  Canaries  and  Azores,  occurs 
in  Bermuda,  but  nowhere  else  in  America.  Another  species 
peculiar  to  Bermuda  (Philoscia  bermudensis)  is  closely 
related  to  the  west  European  Philoscia  couchi.  The 
American  affinities  are  likewise  surprisingly  interesting. 
Uropodias  seems  to  be  related  to  the  West  Indian  genera 
Haplarmadillo  and  Sphaeroniscus,  and  this  strikingly  distinct 
genus  is  quite  confined  to  Bermuda  with  the  one  species,  Uro- 
podias bermudensis.  The  truly  archaic  Actoniscus  ellipticus, 
which  is  only  known  from  Bermuda  and  from  the  coast  of  the 
mainland  near  New  Haven  and  Long  Island  Sound,  is  one 
of  the  only  two  members  of  the  family  Trichoniscidae.  Its 
distribution  is  suggestive  of  a  former  land  connection  towards 
north-eastern  North  America.  The  other  Actoniscus  is  con- 
fined to  California.  Finally,  Leptotrichus  granulatus,  also 
peculiar  to  Bermuda,  may  be  mentioned  as  the  only  occurrence 
of  a  very  ancient  Old  World  genus  in  America.* 

The  only  native  spider  which,  according  to  Dr.  Verrill,f  was 
mentioned  by  'the  early  writers,  was  the  great  silk  spider 
(Nephila  clavipes).  The  enormous  webs  which  this  spider 
constructs  between  trees  at  a  distance  of  fifty  feet  from  one 
to  another  excited  their  admiration,  and  suggested  to  them 
that  the  threads  might  be  used  in  the  manufacture  of  silk 
tissues.  This  has  actually  been  done  in  Brazil,  I  believe, 

*  Eichardson,  Harriet,  "Isopods  of  Bermuda." 
t  Verrill,  A.  E.,  "Bermuda  Islands,": XL,  p.  829. 


WOOD-LICE   AND   SPIDERS  191 

where  this  spider  occurs.  The  silk  spider  is  known  from 
Brazil,  from  Central  America  as  far  north  as  Texas,  and  from 
Southern  Florida.  Professor  Dahl  *  argues  that  the  group  to 
which  this  species  belongs  already  had  a  wide  range  in  Cre- 
taceous times.  Its  nearest  relation,  Nephila  clavata,  is  pecu- 
liar to  China  and  Japan.  It  is  quite  possible,  therefore,  that 
the  American  form  may  have  existed  since  early  Tertiary 
times.  But,  as  Dr.  Marx  f  observes,  the  spiders  introduced  by 
human  agency  have  not  only  acclimatised  themselves ;  they 
havo  also,  in  a  more  or  less  marked  degree,  driven  away  and 
exterminated  the  indigenous  spider  fauna.  Yet  among  the 
remnants  of  that  ancient  fauna  we  recognise  four  species  that 
are  peculiar  to  Bermuda.  Most  of  the  remainder  are  identical 
with  American  forms. 

One  of  the  most  noteworthy  animals  that  might  be  adduced 
in  favour  of  the  theory  that  Bermuda  represents  the  remnant 
of  a  large  land  surface  once  connected  with  the  mainland  is 
the  land  nemertean  Geonemertes  agricola.  This  very  pecu- 
liar worm  is  found  in  abundance  at  several  distinct  localities 
in  Bermuda.  It  might  be  said  that  this  worm  is  not  of  much 
zoogeographical  value,  since  it  is  able  to  resist  immersion  in 
sea -water  for  some  time.  On  the  other  hand,  it  must  be  re- 
membered that  land  nemerteans  have  an  extremely  discon- 
tinuous range  on  ancient  land  surfaces.  Hence  their  distribu- 
tion is  suggestive  of  great  antiquity.  Nine  species  of  the 
genus  Geonemertes  are  now  known  from  Australia,  New  Zea- 
land, New  Guinea,  Pelew  Islands,  Eodriguez  Island,  the 
Seychelles  and  Bermuda.  To  suggest  that  Geonemertes 
agricola  owes  its  presence  in  Bermuda  to  an  accidental  intro- 
duction would  be  quite  inadmissible,  because  it  has  neveu 
been  found  elsewhere. J 

Of  greater  importance  than  any  of  the  foregoing  inverte- 
brates are  the  land  and  fresh-water  snails  inhabiting 
Bermuda.  Dr.  Pilsbry  distinguishes  autochthonous  species, 
drift  waifs  from  the  West  Indies,  and  snails  imported  by  the 
agency  of  man.  The  last  group  we  need  not  consider  here, 

*  Dahl,  F.,  "  Verbreitung  d.  Spinnen,"  p.  278. 
t  Marx,  G.,  "  Spiders  of  Bermuda,"  p.  100. 
|  Coe,  W.  E.,  "  Geonemertes  agricola,"  p.  534. 


192  ORIGIN   OF   LIFE   IN   AMERICA 

although  some  .members  of  it  are  probably  indigenous.  The 
remainder  include  several  snails,  only  once  recorded,  and 
not  again  found  on  the  island  in  recent  times.  iThe 
so-called  waifs  from  the  West  Indies  are  of  greater  signific- 
ance. Dr.  Pilsbry  identifies  Succinea  bermudensis  with 
S.  barbadensis,  yet  acknowledges  that  the  shells  of  this 
genus  are  peculiarly  uncharacteristic,  and  that  species  of 
different  regions  frequently  resemble  each  other.  All  oon- 
chologists,  however,  are  agreed  that  the  semi-amphibious 
amber-snail  (Succinea),  with  its  almost  world -wide  distribu- 
tion, must  be  a  very  an,cient  one.  The  mere  fact  of  several 
Bermudan  species  being  identical  with  West  Indian  ones 
is  no  proof  that  they  were  conveyed  to  Bermuda  by  accidental 
means  of  transport.  I  have  argued  this  point  again  and  again, 
but  it  is  a  widespread  assumption  which  can  only  be  effectu- 
ally disproved  by  palaeontological  evidence.  No  such  evidence 
is  available  in  the  majority  of  cases.  Yet  of  some  of  these  sup- 
posed accidentally  and  recently  introduced  species  of  Bermuda 
I  might  mention  Rumina  decollata.  It  is  certainly  native  in 
the  Mediterranean  region,  where  it  exists,  as  a  relict  o£ the. past, 
and  I  have  given  a  map  of  its  range  in  my  work  on  European 
animals.*  The  family  Stenogyridae,  to  which  it  belongs,  is 
an  entirely  tropical  one.  Rumina  decollata  has  adapted  itself 
to  the  European  climate,  though  its  shape  has  remained  un- 
changed since  Oligocene  times.  It  has  been  known  to  exist 
outside  Europe  in  Cuba,  South  Carolina  and  Bermuda.  Are 
we  justified  in  the  assumption  that  this  exceedingly  old 
member  of  a  tropical  family  of  snails  has  been  accidentally 
introduced  into  these  localities  ?  I  think  not,  and  yet  this 
surmise  is  received  by  almost  everybody  as  an  established 
fact. 

The  really  interesting  members  of  the  Bermudan  fauna  of 
mollusks  are  those  styled  "autochthonous"  by  Dr.  Pilsbry, 
viz.,  Helicina  convexa,  Thysanophora  hypolepta,  all  the 
species  of  Poecilozonites,  and  the  slug  Veronicella  schivelyae. 

I  have  already  dwelt  upon  the  distribution  of  the  genus 
Helicina  (p.  158),  and  on  its  occurrence  in  the  Oligocene 
Silex  beds  of  Tampa  in  Florida,  and  have  indicated  that  it 

*  Scharff,  E.  F.,  "European  Animals,"  p.  222. 


SNAILS  OF  BEKMUDA  193 

represents  a  relict  of  early  Tertiary  times.  The  ancestors  of 
Helicina  convexa,  which  is  peculiar  to  Bermuda,  reached  the 
island  presumably  in  the  Oligocene  Period,  when  we  know 
that  the  genus  inhabited  the  island  of  Florida. 

Thysanophora  is  a  member  of  the  large  family  of  Helicidae. 
It  is  most  characteristic  of  the  West  Indian  region  and  Central 
America,  and  Dr.  Pilsbry  *  declares  that  it  represents  the 
oldest  stock  of  the  West  Indian  Helix  fauna.  The  ancestors 
of  Thysanophora  hypolepta  may  well  have  wandered  to  the 
Bermudan  area  from  the  West  Indian  region  in  early  Tertiary 
times.  This  suggestion  is  strengthened  by  the  fact  that  along 
with  Succinea  and  Poecilozonites  it  is  found  fossil  in  the 
"  red  earth."  The  genus  Poecilozonites,  with  its  four 
Bermudan  species,  is  peculiar  to  Bermuda.  Recently  Pro- 
fessor Boettger  f  again  drew  attention  to  the  intimate  rela- 
tionship existing  between  this  genus  and  the  German  lower 
Miocene  Helix  imbricata,  in  spite  of  Dr.  Pilsbry's  plea  that 
the  German  savant  was  only  chasing  an  "  ignis  fatuus."  Dr. 
Pilsbry  J  prefers  to  derive  Poecilozonites  from  an  old 
American  stock,  arguing  that  it  is  related  to  Gastrodonta.  To 
trace  the  exact  affinity  of  a  recent  to  a  fossil  form  is  always 
a  matter  of  considerable  difficulty,  but  since  several  other 
European  palaeontologists  have  dwelt  upon  the  remarkable 
and  undoubted  relationship  existing  between  the  present  West 
Indian  fauna  and  the  fauna  of  the  European  early  Tertiary 
deposits,  and  as  I  shall  be  able  to  bring  forward  additional 
evidence  in  favour  of  their  views,  I  am  certainly  on  Professor 
Boettger's  side  in  this  controversy.  That  Poecilozonites  is 
not  a  recent  arrival  from  elsewhere,  quite  apart  from  the  fact 
that  it  is  unknown  outside  the  Bermudan  area,  is  likewise 
indicated  by  its  fossil  occurrence  in  the  red  earth,  which' 
is  held  to  be  of  Miocene  or  Pliocene  age.  Dr.  Gulick  §  records 
eleven  species  and  sub-species  of  Poecilozonites  from  the  red 
earth,  as  well  as  Succinea  bermudensis  and  a  number  of 
genera  that  have  since  become  extinct. 

*  Pilsbry,  H.  A.,  "  Manual  of  Conchology,"  Vol.  IX.,  p.  56. 
t  Boettger,  O.,  "  Helix- Arten  aus  d.  Tertiar  Europas,"  p.  103. 
I  Pilsbry,  H.  A.,  "Mollusks  of  Bermuda,"  pp.  491—509. 
§  Gulick,  A.,  "  Fossil  Land  Shells  of  Bermuda." 
L.A.  O 


194  ORIGIN   OF   LIFE   IN   AMERICA 

Mr.  Vanatta  *  recently  made  the  interesting  discovery  that 
several  typical  fresh-water  species  inhabit  Bermuda.  Among 
them  there  is  a  Physa,  two  Planorbis,  one  Ancylus,  a  Palu- 
destrina  and  a  Pisidium.  All  are  new  to  science. 

The  genus  Veronicella  (Vaginula),  of  which  a  species  (Y. 
schivelyae)  inhabits  Bermuda,  includes  slug-like  creatures 
which  should  certainly  not  be  suitable  for  accidental  dispersal 
by  the  usually  quoted  agencies.  It  is  of  interest,  therefore,  to 
note  that  Messrs.  Robbing  and  Cockerell  f  record  a  variety  of 
the  Bermudan  Veronicella  from  the  Bahama  islands,  and 
direct  attention  to  its  close  relationship  with  the  Mexican 
Veronicella  moreleti. 

From  the  foregoing  brief  survey  of  the  Bermudan  fauna  it 
is  manifest  that  although  that  most  destructive  of  all  creatures 
"  man,"  has  played  havoc  with  the  native  animals  and  plants, 
largely  exterminating  them,  a  recognisable  residue  has  sur- 
vived from  remote  times.  As  far  as  the  ancestry  of  this  relict 
fauna  can  be  traced,  it  seems  to  be  derived  from  the  south- 
eastern and  north-eastern  States  of  America,  from  the  West 
Indies  and  even  from  southern  Europe.  Many  species,  par- 
ticularly such  as  are  unfit  to  take  advantage  of  accidental 
modes  of  transport,  namely,  the  Bermudan  skink,  the 
terrestrial  nemertean  worm,  and  various  kinds  of  terrestrial 
isopods  and  snails,  are  peculiar  to  Bermuda.  Is  there  any 
reason  for  the  supposition  that  these  animals,  all  of  which 
bear  the  impress  of  vast  antiquity  on  them,  were  conveyed 
to  Bermuda  in  the  past  by  accidental  means  ?  We  have  no  evi- 
dence whatever  that  terrestrial  invertebrates  are  transported 
alive  across  seven  hundred  miles  of  sea  and  subsequently  pro- 
pagate their  kind  except  through  the  agency  of  man.  Why 
should  we  assume,  therefore,  that  Bermuda  has  received  its 
entire  fauna  and  flora  by  accidental  means  such  as  winds, 
hurricanes  or  ocean  currents  ?  It  is  evident  that  the  great 
depths  of  the  ocean  surrounding  the  little  group  of  islands  is 
the  chief,  if  not  the  sole,  stumbling  block  to  the  acceptance 
of  the  survival  theory.  Yet  in  view  of  the  fact  vouched  for  by 


*  Vanatta,  E.  G.,  "Bermuda  Shells,"  pp.  668—672. 
t  Bobbins,  W.  W.,  and  T.  D.  A.  Cockerell,  "Veronicella,"  p.  383 
384. 


OEIGIN   OF   BEKMUDA  195 

Professor  Suess,  that  a  subsidence  of  land  amounting  to 
10,000  feet  has  taken  place  between  the  island  of  Khodes  and 
the  mainland  of  Syria  in  post-Pliocene  times,  whereas  marine 
deposits  of  late  Pliocene  age  occur  in  the  southern  Andes  at 
a  height  of  5,000  feet,  is  it  really  such  an  unlikely  theory  that 
the  supposed  ancient  belt  of  land  connecting  Bermuda  with 
a  southern  land-mass  has  subsided  to  a  similar  extent  within 
comparatively  recent  geological  times  ?  I  need  not  dwell  any 
longer  on  this  problem.  When  I  come  to  deal  with  the 
Antilles  and  the  origin  of  their  fauna  further  allusions  to  it 
will  be  made. 


o2 


CHAPTER  IX 

SOUTH-WESTERN    NORTH    AMERICA 

THE  region  to  be  dealt  with  in  this  chapter  is  of  enormous 
extent.  To  speak  of  it  vaguely  as  south-western  North 
America  is  apt  to  give  the  impression  as  if  only  Texas 
and  the  adjoining  western  States  "were  being  considered. 
What  is  described  here  under  that  designation  contains  almost 
the  whole  of  the  western  States  with  Mexico  in  addition. 
There  is  material  enough  for  several  chapters.  Nevertheless, 
the  profound  zoogeographical  importance  of  this  portion  of 
North  America  will  be  more  readily  realized,  I  think,  if  the 
leading  facts  are  compressed  into  one  brief  essay.  The  Rocky 
Mountain  fauna,  moreover,  which  enters  largely  into  the 
south-western  region,  has  already  formed  the  substance  of  a 
special  chapter. 

The  term  "  Sonoran  Region  "  was  first  applied  by  Pro- 
fessor Cope  to  part  of  this  important  south-western  life  area, 
because  he  recognised  the  striking  difference  it  presented  as 
compared  with  other  parts  of  the  United  States.  In  one  of  the 
previous  chapters  I  alluded  to  the  scarcity  of  lizards  in  the 
eastern  States  in  comparison  with  western  Europe.  I  might 
have  said  "  western  States  of  North  America  "  instead  of 
western  Europe,  for  lizards  especially,  and  reptile  life  in 
general,  abound  in  the  region  we  are  now  considering. 

The  term  "  Sonoran,"*  derived  from  Sonora,  a  province  of 
northern  Mexico,  is  now  often  applied  to  the  fauna  of  the 
whole  of  North  America  excejpt  the  boreal  portion ;  and  Pro- 
fessor Carpenter  f  supports  the  contention  that  the  continent 
can  be  readily  divided  into  two  faunistic  sections,  one  of  which 
is  distinctly  autochthonous,  the  other  derived  from  northern 
Europe  and  Asia.  I  have  already  put  forward  my  reasons  for 

*  Merriam,  0.  H.,  "Distribution  of  Life  in  North  America,"  p.  26. 
t  Carpenter,  GL  H.,  "Nearctic  or  Sonoran  ?"  pp.  53—57. 


SONORAN   REGION  197 

abandoning  faunistic  regions  in  a  work  of  this  kind,  and  I 
feel  there  is  little  advantage  in  discussing  the  merits  of  one 
regional  system  above  another.  I  only  wish  to  direct  attention 
to  the  fact  that  the  distinctness  and  importance  of  this  south- 
western part  of  North  America  had  long  ago  been  recognised 
by  zoologists.  Professor  Carpenter  urges  that  two  distinct 
faunas  exist  in  America.  I  can  trace  even  more  than  two, 
for  a  South  American  element  is  very  prominently  diffused 
throughout  a  large  portion  of  the  States.  I  cannot  concur 
at  all  in  Dr.  Merriam's  view*  that  "except  for  the. 
presence,  chiefly  in  the  southern  United  States,  of  a  compara- 
tively few  forms  derived  from  the  tropical  region,  the  fauna 
and  flora  of  North  America  are  as  distinctive  and  indepen- 
dent of  the  existence  of  this  area  as  if  separated  from  it  by 
the  broad  ocean."  To  place  ourselves  within  fixed  and 
strictly  limited  boundaries  at  all  seems  to  me  a  mistake.  I 
do  not  limit  myself  in  any  way  to  political  frontiers,  and 
if  I  had  set  myself  a  boundary,  I  should:  have  been  inclined  to 
place  it  across  the  isthmus  of  Tehuantepec.  At  this  point 
North  America  was  evidently  separated  for  some  time  from; 
Central  America  by  a  marine  channel,  though  this  division 
was  not  so  effectual  in  keeping  two  great  faunas  distinct  as 
one  might  expect.  All  this,  however,  will  be  discussed  at 
greater  length  when  we  come  to  deal  with  the  fauna  of  Central 
America. 

Although  vast  tracts  of  south-western  North  America  are 
nothing  more  than  deserts,  there  is,  on  the  whole,  an  extra- 
ordinary abundance  and  variety  of  animal  life.  I  have 
repeatedly  pointed  out  in  previous  chapters  that  the  roots 
of  certain  groups  of  eastern  animals  must  be  looked  for  in 
the  south-west  or  west.  In  drawing  attention  to  the  strange 
affinities  of  some  apparently  very  ancient  east-American 
forms,  such  as  the  smooth  and  the  rough  green  snakes,  and 
east-Asiatic  snakes,  I  urged  that  they  must  originally  have 
spread  eastward  from  south-western  North  America  (p.  125). 
Among  the  tortoises,  too,  certain  eastern  groups  can  be 
traced  to  a  remote  western  origin,  although  no  longer, 
resident  there.  Thus  there  has  arisen  a  comparatively  modern 
repetition  of  that  dissimilarity  between  the  eastern  a,nd 

*  Merriam,  0.  H.,  "  Distribution  of  Life  in  North  America,''  p.  37. 


198  OKIGIN   OF  LIFE   IN   AMEKICA 

western  faunas  which  was  the  characteristic  feature  of  the 
two  ancient  land-masses  during  Mesozoic  times  when  the 
latter  were  separated  from  one  another  by  a  wide  ocean. 
Dr.  Pilsbry  *  once  advocated  the  view,  from  a  conchological 
standpoint,  that  the  Sierra  Nevada  divided  North  America 
into  two  primary  f  aunal  provinces,  a  division  which  he  thought 
commenced  in  Jurassic  times  with  the  upheaval  of  this  moun- 
tain range,  the  latter  having  proved  insurmountable  to  most 
land  snails.  The  true  autochthonous  American  fauna  east 
of  the  Sierra  Nevada  range  seemed  to  him  to  have  developed, 
with  very  little  or  no  trace  of  Old  World  influence,  from  an 
early  period,  probably  the  Cretaceous. 

This  -difference  between  the  east  and  west  is  in  many 
respects  less  pronounced  when  we  include  Mexico  in  our 
western  district.  Few  species  of  the  characteristically 
eastern  snail  Polygyra  are  found  in  California.  Further 
south,  however,  in  Mexico,  their  numbers  again  increase.  The 
family  of  perches (Percidae)  are  quite  absent  from  the  western 
States.  In  Mexico  they  again  appear.  Among  the  garpikes 
(Lepidosteus)  and  the  Unionidae  we  notice  a  similar  distribu- 
tion, but  it  is  not  discontinuous.  Their  range  passes  gradu- 
ally from  the  Gulf  States  into  Mexico.  Among  other  groups 
or  genera  a  greater  discontinuity  of  distribution  is  noticeable 
between  the  Mexican  and  the  east  American  centres  of  dis- 
persal. The  tribes  that  are  affected  by  desert  conditions, 
and  many  of  them  are,  would  find  the  arid  regions  lying 
directly  to  the  north  of  Mexico  effectual  barriers  to  dispersal 
in  that  direction.  But  we  have  good  reasons  for  the  belief  that 
these  desert  conditions  are  comparatively  modern  develop- 
ments, and  have  little  to  do  with  the  origin  of  the  distribution 
referred  to.  The  geological  history  of  the  south-western 
States  may  throw  further  light  on  this  problem. 

From  Cambrian  to  Jurassic  times  the  greater  part  of  Cali- 
fornia was  raised  above  sea-level.  Towards  the  end  of  the 
Mesozoic  Era  there  existed  in  western  North  America  a 
broad  strip  of  land  running  north  and  south  being  bounded 
on  each  side  by  the  sea.f  Mexico  must  have  extended  further 

*  Pilsbry,  H.  A.,  "  Check-list  of  Land  Shells,"  pp.  194—195. 
t  Schuchert,  Charles,  "  Paleogeography  of  North  America." 


CALIFOKNIAN   PALAEOGEOGEAPHY  199 

west  at  that  time,  since  no  late  Mesozoic. deposits  are  known 
from  the  western  parts  of  that  country.  If  we  supposed  that 
western  Mexico  had  then  been  connected  with  some  other 
land  surface,  a  faunistic  interchange  could  have  taken  place 
between  the  latter  and  western  North  America. 

In  early  Tertiary  times  the  central  sea,  which  formed  the 
eastern  boundary  of  the  western  belt  of  land  referred  to,  had 
almost  disappeared  from  the  interior  of  America,  but  large 
tracts  of  western  California  were  still  under  water  (see 
Fig.  14).  Professor  Smith*  argues  that  a  temporary  con- 
nection must  have  existed  during  the  Eocene  Period  between 
the  Atlantic  and  the  Pacific  Ocean,  because  the.  cha- 
racteristic Atlantic  shell  Venericardia  planicosta  had  been 
met  with  in  the  Eocene  deposits  of  California  and  Oregon. 
In  Oligocene  and  Miocene  times  the  whole  of  the  eastern 
borders  of  Mexico  were  submerged,  while  the  sea  was  at 
first  retreating  from  western  California  and  then  again 
invading  it.  During  the  latter  part  of  the  Miocene  Period 
the  sea  even  encroached  on  western  Mexico,  f  All  the 
same,  certain  parts  of  the  coast  ranges  in  western  Cali- 
fornia never  seem  to.  have  been  entirely  submerged  during 
Tertiary  times  and  probably  formed  part  of  the  Pacific  land 
belt  which  has  now  almost  entirely  vanished.  I  think 
the  alternative  union  and  disruption  of  these  western  Cali- 
fornian  land-masses  with  the  mainland  of  North  America 
must  have  played  an  important  role  in  the  origin  and 
development  of  the  American  fauna.  It  seems  as  if  Mexico 
had  at  first  formed  the  stepping-stone  to  North  America  for 
new  immigrants,  and  later  on  western  California.  I  have 
endeavoured  to  represent  this  idea  on  two  maps  (Figs.  14  and 
16),  but  how  the  changes  were  actually  brought  about  has  not 
been  made  quite  clear  to  us  through  geological  research. 

It  has  been  suggested  by  Messrs.  Ordonez  and  Aquilera  that 
the  Cape  portion  of  lower  California  really  forms  the  western 
continuation  of  the  Mexican  Sierra  del  Sur.J  But  the  very 
important  question  now  arises  from  a  zoogeographical  point 

*  Smith,  Perrin,  "  Geological  History  of  California,"  pp.  347—348. 
t  Arnold,  Ealph,  "  Tertiary  Pectens  of  California." 
I  Suess,  E.,  "  Antlitz  d.  Erde,"  III2,  p.  487. 


200  ORIGIN   OF  LIFE  IN]  AMERICA 

of  view,  how  far  westward  and  southward  of  the  Gulf  of  Cali- 
fornia did  this  land  extend  ?  No  Cretaceous  or  Tertiary 
deposits  have  yet  been  discovered  on  the  greater  portion  of 
the  Pacific  coast  of  Central  America.  Geological  evidence  is, 
therefore,  rather  in  favour  of  the  supposition  that  this  western 
land  formerly  extended  further  south. 

As  regards  the  present  arid  semi-desert  conditions  of 
Arizona  and  New  Mexico,  they  supported  in  early  Tertiary 
times,  as  I  have  already  mentioned,  a  wealth  of  animal 
life.  In  the  neighbouring  state  of  Colorado  the  wonderfully 
preserved  impressions  of  insects  in  the  volcanic  tuffs  of 
Florissant,  which  have  been  described  by  Dr.  Scudder  and 
more  recently  by  Professor  Cockerell,*  leave  no  doubt  as  to  the 
former  climatic  conditions  of  that  part  of  America  and  its 
suitability  for  plant  and  animal  life.  The  vast  outpouring 
of  lava  and  general  volcanic  disturbance  in  the  Rocky  Moun- 
tain region  continued  through  Miocene  and  partly  through 
Pliocene  times.  All  the  same,  the  immigration  of  tropical 
types  of  mammals  from  South  America  into  the  Western 
States  at  that  time  would  seem  to  imply  the  existence  in  the 
latter  of  a  luxuriant  flora.  Even  in  Pleistocene  times  an 
abundance  of  large  mammals,  such  as  elephants  and  masto- 
dons, existed  in  southern  California,  and  probably  in  the 
neighbouring  States,  to  judge  from  the  number  of  sabre- 
tooth  tiger  remains  recently  discovered  in  the  asphaltum 
beds  of  Rancho  la  Brea  near  Los  Angeles.  The  gradual 
desiccation  noticeable  in  some  of  the  south-western  States 
is  obviously  a  recent  development,  though  the  abundance 
and  diversity  of  cactuses  and  of  reptiles  adapted  to  a  desert 
life  imply  that  local  arid  areas  must  have  existed  for  long 
ages  past. 

If  the  geological  history  of  the  extreme  south-west  of  North 
America  has  been  correctly  interpretated  in  this  very  brief 
summary,  we  should  certainly  find  relicts  of  ancient  animal 
and  vegetable  types  in  some  of  the  western  areas  that  have 
remained  unsubmerged  during  Tertiary  times.  For  although 
most  animals  would  tend  to  spread  from  these  old  centres  as 
new  land  became  available  for  their  dispersal,  some  of  the 

*   Cockerell,  T.  D.  A.,  "  Fossil  Fauna  and  Flora  of  Florissant." 


SOUTH-WESTEBN  INSECTIVOEES  201 

less  active  and  less  vigorous  types  must  have  remained  in  their 
ancient  western  habitats. 

Among  the  order  Insectivora  which  is  now  on  its  way 
towards  extinction,  several  peculiar  mammals,  such  as 
Atophyrax,  Notiosorex  and  Scapanus  are  entirely  western 
in  range.  The  most  noteworthy  is  what  has  been  called  the 
mole-shrew  (Neurotrichus),  on  account  of  its  shrew-like  look 
combined  with  its  digging  habits.  The  single  species  Neuro- 
trichus gibbsi  is  a  western  rather  than  a  south-western 
animal,  being  confined  to  northern  California  and  Washington 
State.  It  has  no  near  relations  in  America.  Its  nearest  akin 
inhabit  eastern  Asia  and  Europe,  but  it  has  not  yet  been 
(Satisfactorily  established  to  which  of  its  two  Old  World 
tranches  it  has  most  affinity.  The  whole  group  to  which  all 
these  insectivores  belong  is  known  from  the  European 
Eocene  onward.  Nowhere  else  have  fossils  been  found. 
Palaeontological  evidence  would,  therefore,  point  to  Europe 
as  the  centre  of  evolution.  Possibly  the  ancestors  of  Neuro- 
trichus may  have  originated  somewhere  in  the  Mediter- 
ranean region,  have  crossed  the  Atlantic  by  a  mid-Atlantic 
land  bridge  to  California,  as  I  shall  explain  later  on,  and  have 
then  passed  to  Japan,  where  a  closely  related  genus  occurs. 

The  mole-mice  (Onychomys),  which  are  typical  rodents, 
constitute  a  section  which  has  evidently  originated  in  the 
south-west,  and  has  since  spread  northward  and  eastward  so 
as  almost  to  reach  the  Mississippi,  though  none  of  them  have 
crossed  this  river.  The  wood-rats,  belonging  to  the  genera 
Nelsonia,  Xenomys,  Neotomodon,  Teanopus  and  Hodomys 
are  all  confined  to  small  areas  in  the  south-west.  The  four- 
toed  and  the  five-toed  kangaroo-rats  (Dipodomys  and  Pero- 
dipus)  are  almost  all  peculiar  to  the  south-western  States. 

Among  the  carnivores  with  a  similar  range  may  be  men- 
tioned the  raccoon  foxes  (Bassariscus)  and  the  western  skunks 
(Conepatus). 

The  most  striking  examples  tenanting  the  ancient  south- 
western land  areas  must  be  looked  for,  as  I  remarked,  among 
the  more  sessile  and  slow-moving  creatures.  The  reptiles  and 
amphibians  yield  good  instances.  Among  the  former  the  most 
noteworthy  is  the  so-called  "  Gila  monster,"  a  repulsive,  stout, 
thick-tailed  lizard.  It  has  gained  the  unenviable  notoriety 


202  ORIGIN   OF  LIFE   IN   AMERICA 

of  being  the  only  poisonous  lizard  in  existence.  The  genus 
Heloderma,  to  which  it  belongs,  ranges  from  Mexico,  through 
Arizona,  to  western  Texas.  No  near  relations  of  the  Gila 
monster  are  known,  but  it  possesses  some  distant  affinity  to 
a  lizard  living  in  Borneo. 

Better  known  probably  are  the  horned  toads  (Phrynosoma). 
Owing  to  their  greater  activity  they  have  been  able  to  spread 
much  further  north  and  east  of  their  original  centre  of  dis- 
persal. The  horned-toads  are  lizards  belonging  to  the  large 
and  important  family  Iguanidae  which  has  a  peculiar  dis- 
tribution suggestive  of  great  antiquity,  as  I  have  already  indi- 
cated (p.  126).  I  mentioned  that  the  family  lived  in  America 
as  far  back  as  Cretaceous  times,  and  that  beyond  that  con- 
tinent it  was  only  known  from  the  Fiji  Islands  and  Mada- 
gascar. Leaving  the  latter  out  of  consideration  for  reasons 
stated  (p.  126),  we  have  only  to  discuss  the  origin  of  the  Fiji 
members  of  the  family.  The  geological  history  of  the  Poly- 
nesian fauna  will  be  fully  dealt  with  in  a  subsequent  chapter. 
I  may  mention,  however,  that  I  believe  in  the  former  exist- 
ence of  an  ancient  circum -Pacific  belt  of  land  which  was 
joined  to  south-western  North  America  (Fig.  14),  and  that 
the  Iguanidae  passed  across  this  land  during  their  wanderings 
from  America  to  Fiji  or  vice  versa. 

Let  us  turn  from  the  active  Iguanidae,  and  take,  as  an 
example,  a  slowly-moving  creature  such  as  the  Californian 
limbless  lizard  Anniella.  It  inhabits  barren  sand-dunes,  lying 
buried  in  the  sand  and  exposing  only  the  anterior  part  of  the 
head.*  Not  only  is  it  a  reptile  which  spreads  very  slowly,  but 
it  is  eminently  an  animal  requiring  a  continuous  land  surface 
for  its  dispersal.  As  might  be  expected,  the  genus  Anniella 
is  quite  peculiar  to  the  south-western  States.  No  other 
member  of  the  family  Anniellidae  is  known,  though  it  is 
closely  related  to  the  Anguidae,  which  are  almost  confined  in 
their  distribution  to  America  and  Europe. 

We  also  possess  a  single  species  of  tha,t  remarkable  family 
of  burrowing  lizards,  the  Amphisbaenidae,  in  lower  California 
and  Mexico,  viz.,  Euchirotes  biporus.  It  is  a  significant  fact 
that  two  peculiar  genera  of  that  ancient  family  occur  in  the 

*  Coe,  W.  E.,  and  B.  W.  Kunkel,  "  Californian  Limbless  Lizard," 
pp.  350—351. 


BUKBOWING  LIZARDS  203 

two  southern  corners  of  North  America,  one  (Rhineura) 
in  Florida,  the  other  (Euchirotes)  in  Lower  California  and 
Mexico.  The  only  North  American  members  of  the  blind 
snakes  (Glauconiidae)  are  limited  in  their  range  to  the  south- 
western States.  One  of  them  (Glaucoma  dulcis)  lives  in 
Mexico,  New  Mexico  and  Texas,  the  other  (Glaucoma  humilis) 
ranges  from  California  as  far  as  Arizona.  These  degenerate 
worm-like  creatures  are  entirely  subterranean,  and  feed  on 
earthworms  and  larvae  of  insects.  Hence  their  distribution 
is  of  great  zoogeographical  value.  Besides  the  districts  re- 
ferred to  the  family  is  found  in  the  Lesser  Antilles,  Central 
and  South  America,  south-western  Asia  and  Africa.  That 
these  snakes  should  have  passed  all  through  the  continent  of 
North  America  and  through  northern  Asia  in  spreading  from 
South  America  to  Africa  or  vice  versa  without  leaving  a  trace 
of  their  former  wanderings  seems  to  me  very  unlikely. 
Yet  geographical  distribution  of  that  kind  is  frequently  ex- 
plained by  the  supposition  of  a  former  Bering  Strait  land 
bridge  offering  the  only  means  of  land  communi cation  between 
the  Old  World  and  the  New.  There  being  no  fossil  evidence 
to  guide  us,  we  must  judge  such  cases  altogether  from  the 
present  distribution,  and  it  appears  to  me  that  an  ancient 
land  bridge  across  the  mid-Atlantic  explains  the  latter  more 
satisfactorily  than  the  other  hypothesis. 

The  theory  of  the  former  existence  of  such  a,  land  bridge  is 
not  built  upon  a  single  instance  of  distribution.  I  have 
mentioned  many  others  in  previous  chapters,  and  I  shall 
allude  to  several  in  subsequent  ones.  One  other  striking 
example  may  appropriately  be  mentioned  here,  viz.,  the  dis- 
tribution of  the  boas  (Boidae) .  These  are  mostly  large  and 
active  snakes.  Nevertheless,  they  are  related  to  the  small 
and  slowly-moving  blind  snakes,  because,  like  them,  they  pos- 
sess rudiments  of  a  hip-bone  and  hind  limbs.  Boas  inhabit 
all  tropical  and  sub-tropical  countries.  Only  in  two  dis- 
tricts do  they  pass  into  temperate  climates,  viz.,  in  the  south- 
western States  of  North  America  and  in  south-eastern 
Europe.  In  these  countries  are  found  the  two  closely-allied 
genera.  Lichanura  and  Eryx.  One  of  the  North  American 
boas  (Lichanura  trivirgata)  is  confined  to  the  extreme  south 
of  Lower  California,  another  to  southern  California  and 


204  ORIGIN   OF   LIFE    IN   AMERICA 

Arizona,  while  a  third,  the  rubber  boa  or  silver  snake  actually 
passes  into  Washington  State  and  central  Nevada. 

The  recent  increase  of  dryness  in  the  south-west  has  no 
doubt  affected  the  original  fauna  considerably.  Semi-aquatic 
forms  and  aquatic  ones  have  either  been  destroyed  or  forced 
to  take  refuge  in  the  neighbouring  States  where  climatic  con- 
ditions were  more  favourable.  To  this  cause  may  be  attri- 
buted the  present  scarcity  of  amphibians  in  most  of  the  south- 
western districts,  where  many  of  them,  we  may  presume, 
originally  had  their  headquarters.  The  only  American  mem- 
ber of  certain  toads,  which  on  account  of  the  peculiar  shape 
of  their  tongues  have  been  called  Discoglossidae,  occurs  in 
Washington  State  in  western  North  America.  This  family 
has  always  been  looked  upon  with  particular  interest,  because 
to  it  belongs  the  solitary  amphibian  known  from  New  Zealand. 
This  toad  (Liopelma)  must  have  reached  New  Zealand,  ac- 
cording to  Dr.  Stejneger,*  before  Cretaceous  times  by  means 
of  a  very  ancient  land  connection  with  the  north.  The  same 
author  expresses  the  opinion  that  the  Himalayan  Mountains, 
or  rather  the  region  to  the  south-west  of  them,  was  the  ori- 
ginal home  of  these  discoglossoid  toads,  and  that  they  spread 
from  there  to  New  Zealand  and  North  America.  On  the  latter 
continent  we  still  find,  as  I  remarked,  a  single  genus  of  the 
Discoglossidae  (Ascaphus).  The  present  centre  of  dispersal 
of  these  discoglossoid  toads  is  southern  Europe,  since  three 
genera  are  found  there,  viz.,  Discoglossus,  Alytes  and  Bom- 
binator.  The  first  two  are  strictly  European,  whereas  a  single 
species  of  Bombinator  also  inhabits  northern  China  and  Korea. 
Considering  the  fact  that  these  toads  do  not  occur  in  south- 
western Asia,  and  that  both  Discoglossus  and  Bombinator 
have  been  found  in  European  Miocene  beds,  the  Mediter- 
ranean Region  seems  more  likely  to  have  been  the  original 
centre  of  dispersal  than  south-western  Asia.  At  any  rate, 
that  event  leads  us,  no  doubt,  to  the  dim  and  distant  past  of 
the  early  part  of  the  Mesozoic  Era. 

The  allied  family  Pelobatidae  is  likewise  of  great  faunistic 
interest,  as  the  two  genera  Scaphiopus  of  North  America  and 
Pelobates  of  Europe  are  only  distinguished  by  slight  differ  - 

*  Stejneger,  L.,  "Distribution  of  Discoglossoid  Toads,"  pp.  91 — 93. 


SOUTH-WESTEKN   TOADS  205 

ences.  The  spade -foot  toads  (Scaphiopus),  as  they  have  been 
called,  have  their  headquarters  in  Mexico  and  the  south- 
western States,  whence  they  have  spread  northward  along  the 
Pacific  coast  and  eastward  to  the  Atlantic  States.*  One 
species,  the  hermit  spade-foot  (S.  holbrooki)  is  worthy  of 
special  note,  owing  to  its  occurrence  on  Martha's  Vineyard 
Island,  in  view  of  the  remark  I  previously  made  (p.  183) 
that  this  and  other  north-eastern  islands  are  the  remnants 
of  an  ancient  land  mass  formerly  connected  by  land  with  the 
mid-Atlantic  land  bridge. 

The  faunistic  relationship  between  Europe  and  south- 
western North  America  deserves  an  ample  discussion,  being 
one  of  the  most  important  and  noteworthy  features  of  the 
American  fauna.  Besides  the  points  already  referred  to 
there  are  a  few  others  which  throw  light  on  the  nature  and 
origin  of  this  relationship. 

I  do  not  intend  to  dwell  on  the  merits  of  the  various  classi- 
fications which  have  been  adopted  for  the  land  mollusks.  Even 
if  we  base  our  system'  upon  purely  anatomical  grounds,  dif- 
ferent points  of  view  may  sometimes  give  rise  to  considerable 
differences  in  classification.  Thus  Dr.  von  Ihering  f  contends 
that  the  family  Helicidae,  as  far  as  North  America  is  con- 
cerned, is  entirely  confined  to  the  western  States.  Dr. 
Pilsbry,J  on  th,e  other  hand,  in  including  Polygyra  among 
the  Helicidae,  naturally  records  for  that  family  a  very 
different  range. 

Both  authors  agree  in  attaching  great  importance  to  the 
molluscan  fauna  of  the  western  and  south-western  States, 
and  both  are  inclined  to  attribute  its  origin  to  immigration 
from  Asia.  That  Dr.  Pilsbry  supposes  the  mollusks  to  have 
wandered  across  an  old  Bering  Strait  land  bridge,  while  Dr. 
von  Ihering  §  argues  in  favour  of  a  much  more  southern 
Oligocene  land  connection  between  eastern  Asia  and  Cali- 
fornia, is  not  perhaps  of  such  fundamental  importance.  The 
general  agreement  is  all  the  more  remarkable,  as  both 
authors  have  formed  radically  different  views  on  the  interpre- 

*  Gadow,  H.,  "  Mexican  Amphibians  and  Eeptiles,"  p.  205. 
f  Ihering,  H.  von,  "  Yerbreitung  der  Heliciden." 
t  Pilsbry,  H.  A.,  "  Manual  of  Conchology,"  Vol.  IX.,  p.  xxxii. 
§  Ihering,  H.  von,  "  Verbreitung  der  Heliciden,"  p.  442. 


206  ORIGIN   OF   LIFE   IN   AMERICA 

tation  of  some  anatomical  facts.  Dr.  von  Ihering  supports 
the  opinions,  upheld  by  almost  all  the  prominent  European 
concholOgists,  that  the  west  American  shells,  which  so  greatly 
resemble  the  European  Ariantas  and  Campylaeas,  are  really 
genetically  connected  with  the  latter.  He  even  contends  that 
no  anatomical  distinction  worth  mentioning  exists  between 
some  of  the  American  Epiphragmophoras  and  the  European 
Arianta.  Dr.  Pilsbry,  on  the  other  hand,  does  not  recognise 
any  very  intimate  anatomical  relationship  between  the  Euro- 
pean and  west  American  Helicidae,  except  in  so  far  as  he  con- 
siders both  to  be  branches  of  an  ancient  south  Asiatic  stock. 
As  I  shall  explain  later  on,  I  concur  with  Dr.  von  Ihering, 
Dr.  Sandberger,  Professor  Oppenheim,  Professor  Boettger  and 
Dr.  Kobelt  in  the  opinion  that  many  of  the  Antillean  and 
west  American  forms  are  intimately  related  to  extinct  and 
recent  European  Helicidae.  The  great  resemblance  of  the 
shells  of  Arianta  and  some  of  the  Epiphragmophoras  alone 
seem  to  imply  a  near  relationship  between  them. 

The  genera  Ashmunella,  Sonorella  and  Oreohelix  are  quite 
peculiar  to  south-western  America,  a  large  number  of  species 
having  been  described  by  Dr.  Pilsbry  and  Mr.  Ferris  *  in  a 
series  of  articles  contributed  within  the  last  few  years  to  the 
Proceedings  of  the  Academy  of  Natural  Sciences  of  Phila- 
delphia. The  same  region  contains  many  other  distinct  genera 
of  land  mollusks.  The  Urocoptidae,  a  family  of  snails  some- 
what resembling  the  European  Clausilia  in  shape,  and  having 
their  headquarters  in  the  Antilles,  are  represented  by  two 
genera,  viz.,  Holospira  and  Berendtia,  peculiar  to  south- 
western North  America. 

Of  some  interest  is  the  occurrence  in  southern  Mexico,  in 
lower  California,  and  on  the  intervening  islands,,  of  many 
species  of  the  large  and  ponderous  genus  Bulimulus.  The 
difficulty  of  satisfactory  identification  unfortunately  is  such 
that  there  is  little  agreement  among  the  various  authorities  as 
to  the  limits  or  range  of  species,  nor  is  the  nomenclature  of 
these  shells  in  a  more  satisfactory  position.  All  the  same 
as  I  shall  mention  later  on,  we  can  gather  some  useful  hints 
from  their  distribution. 

*  Pilsbry,  H.  A.,  and  J.  H.  Ferris,  "  Mollusca  of  the  South- Western 
States." 


FAUNA  OF   CAPE   EEGION  207 

The  point,  however,  I  wish  to  direct  special  attention  to 
is  the  fauna  as  a  whole  inhabiting  the  southern  part  of  the 
long  peninsula  of  Lower  California.  This  peninsula,  for  which 
many  people  retain  the  Spanish  name  "  Baja  California,"  is 
a  narrow  strip  of  broken  mountainous  land,  nearly  eight  hun- 
dred miles  long,  and  averaging  about  fifty  miles  in  width.  On 
the  western  side  of  this  region  there  are  a  series  of  isolated 
peaks  or  ridges  rising  to  a  height  of  about  2,000  feet.  An 
older  range  of  mountains,  composed  of  granite  and  gneiss,  lies 
along  the  eastern  flank  of  the  peninsula.  Most  of  this  vast 
country  is  bare  and  desert-like,  with  a  scanty  flora,  water 
being  difficult  to  obtain.*  As  soon  as  we  enter  what  is  called 
the  "  Cape  Region  "  all  this  is  changed.  Running  water  can. 
be  procured  throughout  the  whole  year,  in  the  larger  canons 
at  any  rate,  and  this  gives  rise  to  an  extremely  rich  and 
exuberant  vegetation.  While  almoist  the  whole  of  the  fauna 
and  flora  of  the  peninsula  are  merely  a  continuation  of  those 
of  Calif ornia  and  Arizona,  having  evidently  passed  into  it  from 
the  north  and  east,  the  southernmost  tip,  or  Cape  Region,  has 
an  entirely  different  set  of  animals  and;  plants.  I  have  already 
alluded  to  the  occurrence  here  of  Euchirotes  biporus,  a  very 
peculiar  burrowing  lizard  belonging  to  the  ancient  family  of 
Amphisbaenidae,  and  of  the  boa  Lichanura  trivirgata.  Another 
reptile,  which  is  quite  peculiar  to  the  same  district,  is  Cteno- 
saura  hemilopha.  This  great  lizard,  of  nearly  two  feet  in 
length,  possessing  a  high  crest  along  its  back,  a  green  head 
and  pale  yellow  body  spotted  with  olive,  brown  and  black,  is  a 
most  remarkable  and  striking  object.  The  only  near  relations 
of  the  burrowing  lizard,  and  of  the  great  active  Ctenosaura, 
live  in  south-western  Mexico.  But  the  Mexican  forms  do  not 
belong  to  the  same  species.  We  cannot,  therefore,  assume  that 
these  lizards  have  been  accidentally  carried  across  the  Gulf 
of  California,  which  has  a  width  of  about  one  hundred  miles 
near  the  tip  of  the  peninsula.  The  genus  Ctenosaura,  it 
may  be  mentioned,  is  related  to  Cyclura  of  the  West  Indies, 
and  Brachylophus  of  the  Fiji  and  Friendly  Islands,  these 
genera  all  belonging  to  the  great  family  Iguanidae,  which 
has  inhabited  America  since  Cretaceous  times  (p.  202). f 

*  Merrill,  Q-.  P.,  "Lower  Calif  ornia." 

t  Denburgh,  J.  van,  "  Herpetology  of  Lower  California,"  p.  78. 


ORIGIN   OF  LIFE  IN   AMERICA 

The  flora  of  the  Cape  Region  is  sub-tropical,  a  considerable 
proportion  of  the  plants  being  West  Indian.  There  are  also  a 
few  genera  which  do  not  occur  elsewhere  on  the  American 
continent  or  the  neighbouring  islands.  A  small  tree  abun- 
dant in  the  Cape  district  belongs  to  the  genus  Albizzia,  which 
is  otherwise  confined  to  Australia  and  the  warmer  parts  of 
Asia  and  Africa.*  Although  the  lower  Californian  species  is 
quite  distinct,  its  occurrence  there  might  be  attributed  by 
some  naturalists  to  accidental  distribution  by  marine  currents 
during  some  former  period.  No  other  occasional  means 
of  transport  could  be  thought  of.  But  Albizzia  is  by  no 
means  an  isolated  instance  of  floristic  relationship  between 
the  countries  bordering  the  west  and  east  sides  of  the  Pacific 
Ocean.  Difficult  problems  of  distribution  of  that  nature  are 
apt  to  be  looked  upon  as  instances  of  accidental  dispersal. 
Yet  these  puzzling  cases  of  distribution  often  supply  us  with 
valuable  clues  with  reference  to  possible  changes  of  land  and 
water  that  may  have  taken  place.  That  the  Cape  Region  of 
Lower  California  is  really  a  fragment  of  an  ancient  land -mass 
is  suggested  by  the  occurrence  there  of  the  burrowing  lizard 
Euchirotes,  of  two  species  of  the  fresh- water  oligochaet  worm 
Kerria,  and  by  a  good  many  other  faunistic  features.  Kerria 
is  only  met  with  in  that  region,  in  the  West  Indies  and  in 
southern  South  America. 

Among  the  most  interesting  members  of  the  Cape  fauna 
are  the  land  shells  of  the  genus  Bulimulus  above  referred 
to.  Dr.  Cooper, f  in  his  series  of  valuable  papers,  only 
mentions  a  few  species  found  in  that  region,  but  he 
alludes  to  the  noteworthy  fact  that  two  of  the  Bulimuli 
only  live  on  the  peninsula  of  Lower  California,  and  in  a  similar 
situation  on  the  coast  of  southern  South  America,  though  quite 
absent  from  the  intervening  moist  tropical  region.  Dr.  Dall,J 
and  more  recently  Dr.  Pilsbry,  have  shown,  however,  that  the 
Cape  species  are  not  identical  with  the  South  American  ones, 
though  extremely  like  them  in  general  appearance,  and  that 
they,  together  with  those  of  southern  Mexico  and  the  interven- 
ing islands,  form  a  group  by  themselves.  About  twenty  species 

*  Brandegee,  T.  S.,  "Flora  of  Baja  California,"  p.  222. 
t  Cooper,  J.  Gr.,  "  Molluscs  of  Lower  California,"  p.  99. 
t  Ball,  W.  H.,  "  Bulimulus  in  Lower  California." 


SNAILS   OF  CAPE   REGION  209 

of  this  genus  of  large  snails  are  peculiar  to  the  Cape  Region, 
several  others  being  identical  with  Mexican  ones.  Some  of 
them  have  spread  along  the  peninsula  northward,  yet  it 
seems  certain  that  the  Lower  Californian  centre  of  dispersal 
lies  in  the  Cape  district,  for  no  species  occurs  in  California 
proper.  If  we  examine  the  range  of  the  genus  Bulimulus  as  a 
whole,  we  find  that  its  headquarters  are  in  the  West  Indies. 
From  there  it  has  travelled  to  eastern  South  America  possibly 
across  a  very  ancient  land  surface.  Another  branch  has  gone 
westward  and  populated  the  distant  Galapagos  islands.  A 
third  stream  apparently  invaded  the  coast  lands  of  South 
America  from  the  west,  for  we  find  numerous  groups  of  Buli- 
muli  in  certain  western  areas  in  Bolivia,  Peru  and  Chile. 
Still  another  section  has  struck  directly  westward  across 
southern  Mexico  to  the  southern  parts  of  Lower  California. 
A  couple  of  species  have  passed  into  Texas  and  further 
east  from  this  Mexican  centre. 

Considering  that  the  closely  related  genus  Placostylus 
inhabits  New  Zealand,  as  well  as  a  series  of  archipelagoes 
between  it  and  the  Solomon  Islands,  it  must  be  admitted  that 
in  Bulimulus  we  have  to  deal  with  an  almost  archaic  genus, 
and  that  the  land-masses  and  islands  on  which  it  is  now  found 
are  probably  fragments  of  ancient  continuous  lands.  Acci- 
dental dispersal  of  shells  has  formed  the  subject  of  Mr. 
Medley's  *  special  study.  Yet  he  shows  that  the  species,  par- 
ticularly of  the  southern  Placostylus,  being  heavy  massive 
shells,  are  singularly  unfitted  for  crossing  distant  seas  by 
occasional  means  of  dispersal.  Hence  he  arrives  at  the  con- 
clusion that  the  Solomon  and  Fiji  islands,  the  New  Hebrides, 
Loyalty  Islands,  New  Caledonia,  Norfolk  Island,  Lord  Howe 
Island  and  New  Zealand  form  a  zoological  province,  and  are 
to  be  considered  as  the  fragments  of  a  shattered  continent. 

A  similar  argument  might  be  applied  to  Bulimulus,  which  is 
so  closely  related  to  Placostylus.  It  seems  permissible  to 
argue  that  the  West  Indies  in  early  Mesozoic  times  were  a 
large  united  land-mass,  that  the  latter  was  continued  south- 
eastward so  as  to  join  the  archaic  lands  of  eastern  Brazil,  that 
it  swept  westward  across  what  is  now  Central  America  out 
*  Hedley,  0.,  "  Placostylus,"  A  Study  in  Ancient  Geography,  pp.  337— 
339. 

L.A.  P 


210  ORIGIN  OF  LIFE   IN  AMERICA 

into  the  Pacific  Ocean,  and  that  wherever  in  Bolivia,  Peru  and 
Chile  we  find  groups  of  Bulimuli,  the  land  on  which  they  live 
represents  some  portion  or  fragment  of  that  ancient  land 
which  once  occupied  part  of  the  eastern  Pacific  Ocean.  If  we 
had  no  other  data  in  support  of  such  theories,  they  would  be 
based  on  very  slender  evidence.  But  all  this  will  be  more 
amply  discussed  when  we  come  to  deal  with  the  general  fauna 
of  the  Galapagos  Islands  and  western  South  America. 

The  only  other  point  bearing  on  the  westward  extension  of 
the  ancient  "Antillea,"  as  the  supposed  West  Indian  continent 
has  been  called,  is  the  singular  occurrence  here  and  there 
of  traces  indicating  land  westward  of  California.  Along  the 
coast  of  southern  California  lies  a  little  cluster  of  eight  islands 
which  have  lately  attracted  the  attention  of  naturalists. 
Now,  as  Mr.  Greene  informs  us,  on  Santa  Catalina  Island 
may  be  found  Crossosoma,  a  plant  so  peculiar  as  almost  to 
represent  a  distinct  natural  order,  and  more  closely  related 
to  the  Asiatic  and  Australian  Dilleniaceae  than  to  any  plant 
on  the  American  Continent,  except  a  single  congener  recently 
discovered  in  south-eastern  California.  Speaking  of  Santa 
Cruz,  another  of  this  group  of  small  islands,  he  comments  on 
its  unique  feature  in  possessing  no  less  than  forty-eight 
species  of  plants  not  found  on  the  opposite  mainland  and 
expresses  the  opinion  that  the  whole  set  of  islands  must  have 
a  very  peculiar  geological  origin  and  history.  Species  belong- 
ing to  distinctly  Calif ornian  genera,  like  Dendromecon,  Esch- 
scholtzia,  Thysanocarpus  and  Zauschneria,  abound  in  such 
numbers  as  to  suggest  the  question  whether  it  was  no\  from 
these  islands  that  the  mainland  plants  of  the  same  genera 
wer'e  derived.  The  remarkable  fact  that  Lyonothamnus, 
Hazardia  and  the  Lavateras,  all  of  which  have  Asiatic  or 
Australian  affinities,  occur  on  these  islands  in  several  distinct 
species,  being  quite  unknown  on  the  American  continent, 
makes  Mr.  Greene*  wonder  whether  this  group  of  islands 
has  not  formerly  been  connected  by  land  with  some  other 
continent  than  America. 

Surprising  and  apparently  inexplicable  as  this  feature  may 
seem,  California  and  south-western  North  America  generally 

*  Greene,  E.  L.,  '<  Botany  of  Santa  Cruz  Island,"  pp.  377—388. 


EUROPEAN  INVASION  211 

reveal  a  still  more  extraordinary  phenomenon  in  distribution. 
We  may  imagine,  and  many  people  actually  do,  that  the  power 
of  wind  and  wave's  to  carry  objects  from  one  part  of  the  world 
to  another  is  almost  unlimited.  One  of  the  most  striking 
and  remarkable  characters  of  California,  however,  is  its  very 
close  faunistic  affinity  with  western  Europe.  Even  the  most 
enthusiastic  supporter  of  the  flotsam- jetsam  theory  will  feel 
that  some  other  cause  than  this  must  have  been  responsible  in 
producing  this  effect.  A  former  land  connection  between  the 
two  regions,  without  others  being  affected,  seems  out  of  the 
question.  Yet  almost  all-  those  who  have  endeavoured  to 
explain  the  origin  of  this  western  fauna  have  preferred 
to  choose  the  old  Bering  Strait  land  connection  as  offer- 
ing a  safe  passage  to  European  animals,  rather  than 
disturbing  the  general  arrangement  of  the  existing  oceans 
and  continents.  If  the  faunistic  resemblance  of  Cali- 
fornia to  western  Europe  had  really  been  caused  by  a 
migration  of  animals  from  one  area  to  the  other  across  the 
whole  Asiatic  continent,  eastern  Asia  ought  surely  to  show 
affinity  with  California  to  a  much  more  pronounced  degree 
than  western  Europe  does.  As  a  matter  of  fact,  certain 
groups  in  California  are  distinctly  eastern  Asiatic  in  affinity, 
afs  I  have  just  mentioned,  while  others  are  just  as  clearly; 
isouth  and  west  European  in  character.  I  have  given  a  few 
instances  already  of  these  faunistic  relationships,  and  further 
evidence  will  now  be  adduced  in  support  of  this  statement. 

I  think  it  was  the  snail  Arianta  arbustorum,  so  prominently 
alluded  to  in  my  work  on  European  animals,  which  first 
drew  the  attention  of  American  zoologists  to  this  relation- 
ship, for,  as  already  remarked,  a  snail  extremely  similar  in 
appearance  lives  in  California.  Even  Dr.  Pilsbry  *  admits 
that  the  resemblance  in  shell  characters  of  the  Calif  ornian  and 
European  species  is  astonishing,  although  he  adds  that  it 
is  due  to  a  purely  secondary  modification  that  these  shells  have 
been  moulded  to  a  deceptive  likeness,  the  genitalia  having 
been  left  unchanged  to  tell  more  faithfully  the  story  of  their, 
lineage.  Having  made  an  anatomical  study  of  this  Californian 
Arianta -like  group,  Dr.  Pilsbry  arrives  at  the  conclusion  that 

*  Pilsbry,  H.  A.,  "  Manual  of  Conchology,"  IX.,  p.  196.          + 

P2        ''' 


212  ORIGIN   OF   LIFE   IN   AMERICA 

the  latter  belongs  to  the  same  great  family  Helicidae  as  the 
European  Arianta,  but  that  otherwise  it  is  quite  unrelated 
to  it.  He  places  the  Californian  forms,  therefore,  into  the 
genus  Epiphragmophora,  contending  that  its  nearest  rela- 
tions are  the  Helices  of  Japan.  In  another  place  (p.  46)  he 
adds  the  remark  that  it  is  unnecessary  to  throw  land  bridges 
across  the  depths  of  the  Atlantic  and  Pacific  Oceans  to  account 
for  the  distribution  of  Helices.  Such  hypotheses,  he  thinks, 
are  contrary  to  many  facts  indicating  that  such  groups  of 
snails  as  are  common  to  America  and  Europe  have  radiated 
from  an  Oriental  centre  westward  to  Europe  and  eastward, 
by  way  of  a  former  Bering  Strait  land  bridge,  to  America. 
Yet  Dr.  Pilsbry's  conclusions,  as  I  have  already  mentioned, 
are  contested  by  Dr.  von  Ihering  likewise  on  anatomical 
grounds.  Although  Dr.  Pilsbry  maintains  that  his  opponent 
bases  his  deductions  on  "figures  and  not  dissections  (p.  195), 
Dr.  von  Ihering,  in  a  recently  published  paper,  again  insists 
that,  after  having  made  a  careful  anatomical  investigation  of 
Arianta,  (or  Helicigona  as  he  calls  it,)  and  the  American 
Epiphragmophora,  he  could  perceive  no  difference  worth  men- 
tioning between  the  two.  Hence  Dr.  von  Ihering's*  opinion 
is  that  the  American  Helices,  which  are  now  generally  known 
under  the  name  of  Epiphragmophora,  and  which  are  entirely 
confined  to  the  Pacific  coast  of  America,  possess  their  nearest 
relations  not  in  Asia  but  in  western  Europe. 

Let  us  take  another  group,  that  of  the  well-known  Euro- 
pean family  of  slugs,  the  Arionidae.  In  1896  Messrs.  Pilsbry 
and  Vanatta  f  showed  by  anatomical  investigations  that  the 
American  slugs  Ariolimax  and  Aphallarion  belong  to  this 
family.  Later  on  the  same  writers  added  the  genera 
Anadenulus,  Hemphillia,  Hesperarion  and  Prophysaon  to 
this  list.  The  whole  of  this  great  assembly  of  Arionidae 
is  quite  confined  to  the  Pacific  region  between  British 
Columbia  and  southern  California.  No  other  slug  of  this 
family  has  as  yet  been  discovered  anywhere  in  the  New 
World,  except  one  or  two  European  species  in  the  north- 
eastern States,  which  may  either  have  been  introduced 

*  Ihering,  H.  von,  "  System  der  Heliciden,"  p.  422. 
t  Pilsbry,  H.  A.,  and  E.  G.  Vanatta,  "Revision  of  North  American 
Slugs." 


SNAILS   AND   SLUGS   OF   CALIFORNIA        213 

or  have  crossed  over  by  a  former  North  Atlantic  land  bridge. 
In  western  Europe  and  north  Africa  we  have  the  four  genera 
Arion,  Geomalacus,  Ariunculus  and  Letourneuxia.  Only  the 
first  of  these  has  a  wide  range,  one  species  extending  through 
Russia  to  northern  Siberia.  In  Asia  only  a  single  genus 
(Anadenus)  of  the  family  is  known,  inhabiting  the  Hima- 
layan Mountains  and  China.  The  Arionidae  thus  have  a  most 
discontinuous  range,  and  their  origin  and  dispersal  form  an 
interesting  problem.  Since  Geomalacus  and  Letourneuxia 
are  confined  to  the  western  borders  of  Europe  and  North 
Africa,  and  Arion  obviously  has  its  headquarters  in  the  same 
region,  Professor  Simroth  *  argued  that  the  European  Ario- 
nidae had  either  originated  on  a  sunken  land  which  lay  out 
in  the  Atlantic,  or  wandered  across  an  ancient  Atlantis  from 
western  America.  Dr.  Pilsbry  f  also  is  in  favour  of  an 
American  genesis  for  the  Arionidae,  but  he  believes  that 
the  ancestors  of  the  Old  World  genera  just  alluded  to 
must  have  crossed  over  to  Asia  by  means  of  a  former 
Alaskan  land  bridge,  and  then  have  wandered  along,  dropping 
Anadenus  on  the  way,  until  they  finally  reached  western 
Europe.  Of  the  two  theories  Professor  Simroth's  appears 
to  me  the  more  plausible  one.  And  his  hypothesis  is 
strengthened  by  the  occurrence  in  south-western  North 
America  of  a  species  of  slug  either  identical  or  very  closely 
related  to  a  European  one,  viz.,  Amalia  hewstoni.  The  Euro- 
pean Amalia  (Milax)  gagates  must  be  regarded  as  an  exceed- 
ingly ancient  species,  certainly  dating  back  to  beyond  Tertiary 
times.  Geological  evidence  for  such  a  belief  there  is  none, 
nor  could  we  expect  to  find  the  remains  of  slugs  in  ancient 
deposits.  In  a  matter  of  that  kind  we  have  to  rely  purely  on 
distributional  evidence.  That  Amalia  gagates  could  be  trans- 
ported to  any  island  from  the  mainland  by  the  ordinary  means 
of  dispersal  is  out  of  the  question.  It  can  only  have 
reached  its  present  habitat  on  many  very  remote  islands  by 
human  introduction  or  by  former  land  connections  with  the 
mainland.  It  is  by  no  means  a  slug  that  congregates  near 
human  habitations,  nor  is  it  commonly  found  among  vegeta- 
bles like  some  of  the  Limaces  and  Arions.  Yet  it  occurs  in 

*  Simroth,  H.,  "  Nacktschnecken  Russlands,"  p.  60. 
t  Pilsbry,  H.  A.,  "  Phylogeny  of  Arionidae,"  p.  103. 


214     .         OKIGIN  OF  LIFE  IN  AMERICA 

variously  modified  forms  on  the  islands  of  Madeira,  Sicily, 
Sardinia  and  Teneriffe,  on  the  Azores,  the  Cape  Verde  islands, 
St.  Helena,  Tristan  d'Acunha  and  Bermuda.  It  has  never 
been  reported  from  any  of  the  West  Indian  islands,  Central 
America  or  the  southern  States  of  North  America.  In  western 
North  America  it  has  a  wide  range,  being  known  as  Amalia 
hewstoni,  from  British  Columbia  to  Mexico.  On  the  east 
coast  it  occurs  only  along  the  coast  of  Massachusetts  and  New 
York,  exactly  where  so  many  other  members  of  an  ancient 
fauna  reside.  In  Asia,  except  Asia  Minor,  no  Amalia  has 
hitherto  been  discovered.  In  Africa  it  is  only  met  with  along 
the  north  coast  and  in  Cape  Colony  (A.  ponsonbyi).  From 
south  Australia  a  similar  form  has  been  described  as  Amalia 
pectinata,  while  others  occur  in  New  Zealand  and  the  Sand- 
wich islands.  Most  zoologists  will  insist  that  such  an  enor- 
mously wide  and  discontinuous  range  of  a  species,  though 
exhibiting  distinctive  characters  in  its  various  habitats,  can 
only  be  due  to  artificial  introduction  by  man.  My  own  opinion 
is  that  it  has  reached  all  the  localities  referred  to  by  the 
natural  means  of  progression  on  land  during  a  long  series  of 
geological  periods,  and  Professor  Simroth,*  the  best  living 
authority  on  slugs,  shares  the  same  view.  As  far  as  its  occur- 
rence in  western  North  America  is  concerned,  Professor  Sim- 
roth's  Atlantis,  a  land  bridge  connecting  Portugal  with  the 
•West  Indies  and  the  lands  beyond  it  across  the  Atlantic, 
would  suit  our  purpose.  The  slug's  absence  from  the  Antilles 
might  be  due  to  the  fact  that  it  became  extinct  there  during 
the  extensive  submergence  which  the  West  Indian  area  has 
undergone  in  Tertiary  .times. 

The  eminent  authority  on  butterflies  and  moths,  Dr.  Pagen- 
stecher,f  tells  us  that  California  possesses  an  independent 
character  among  the  North  American  fauna,  in  being  more 
nearly  related  to  Europe  than  to  the  eastern  States.  With 
the  exception  of  Ctenucha  and  Agarista  all  the  genera  are 
European,  while  Pyrameis  atalanta,  P.  cardui,  Vanessa 
antiopa,  Arctia  ca'ja,  Phragmatobia  fuliginosa,  Scoliopteryx 
libatrix,  Brachionycha  nubeculosa,  Amphipyra  pyramidea  and 
Agrotis  exclamationis  are  common  to  California  and  Europe. 

*  Simroth,  EL,  "  Pendulations  Theorie,"  p.  92. 

t  Pagenstecher,  A.,  "  Verbreitung  d.  Schmetterlinge,"  p.  359. 


BUTTERFLIES   OF   CALIFORNIA  215 

Among  the  most  abundant  beetles  in  California  there 
is  a  group  of  flightless  forms  which  when  touched  will  emit 
a  pungent,  oily  secretion.  Owing  to  their  curious  habit  of 
elevating  their  bodies  when  alarmed  they  have  received  in  the 
west  the  popular  name  of  "  circus  bugs."  Now  this  section 
Eleodinae  of  the  large  family  Tenebrionidae  are,  in  North 
America,  quite  peculiar  to  the  south-west.  A  few  species  have 
spread  northward  into  Washington  State  and  eastward  as  far 
as  the  Mississippi.  The  great  mass  of  these  thick-bodied  oily 
creatures  lives  in  Mexico  and  California,  where,  according  to 
Mr.  Blaisdell,*  they  have  probably  originated.  The  only  near 
relation  of  this  south-western  group  in  the  New  World  is  the 
genus  Nycterinus,  which  is  peculiar  to  Chile.  But  throughout 
the  Mediterranean  Region  we  meet  with  a  very  large  number 
of  similar  beetles,  commonly  called  "  oil  beetles,"  and 
although  many  of  them  are  also  found  in  Persia,  Turkestan, 
Central  Asia  and  even  China,  south-eastern  Europe  must  be 
looked  upon  as  the  headquarters  of  the  genus  Blaps,  to  which 
they  belong. 

The  same  family  Tenebrionidae  also  offers  instances  of 
intimate  relationship  between  the  Antilles  or  Central  America 
and  southern  Europe.  I  need  only  recall  the  American 
Gnathocerus  maxillosus  which  likewise  inhabits  Madeira,  the 
Canary  and  Mediterranean  islands,  as  well  as  Sitophagus 
hololeptoides  of  Central  and  South  America,  the  Antilles  and 
Madeira. 

Dr.  Kolbe  f  mentions  similar  examples  of  distribution 
among  the  coprophagous  lamellicorn  beetles.  Thus  Oniti- 
cellus  and  Grlaresis  are  quite  peculiar  to  the  south-west  in 
North  America,  whereas  in  Europe  they  are  confined  to  the 
Mediterranean  Region.  Only  the  former  has  spread  further 
southward  into  Africa  and  eastward  into  Asia. 

Of  all  the  insects,  faunistically  the  most  interesting  are 
the  ants.  In  my  work  on  European  animals  I  alluded  to 
Stenamma  westwoodi  as  one  of  the  members  of  the  Lusitanian 
fauna,  which  penetrated  as  far  north  as  south-western  Ire- 
land. The  same  species  is  met  with  in  America  in  a  few 
varieties.  One  lives  in  California,  the  other  in  British 

*  Blaisdell,  F.  E.,  "Eleodinae  of  the  United  States,"  pp.  28—29. 

t  Kolbe,  H.  J.,  "  Verbreitung  d.  Coprophagen  Lamellicornier,"  p.  499. 


216  OKIGIN   OF   LIFE   IN   AMERICA 

Columbia,  the  third  in  the  north-east.*    Honey-ants,  at  least 
certain  members  of   their   colonies,    possess  the  faculty  of 
storing  quantities  of  honey  within  their  bodies,  which  swell 
up  to  a  great  size,  and  on  that  account  are  somewhat  remark- 
able objects.     In  North  America  two  species  of  honey-ants 
occur,  namely,  Myrmeocystus  melliger  and  M.  mexicanus, 
both  being  confined  to  Mexico,  Arizona  and  the  neighbouring 
regions.     The  other  species  of  the  genus  Myrmeocystus  in- 
habit the  Mediterranean  Region  and  further  east  as  far  as 
central  Asia.f     In  southern  Europe  a  soft,  velvety  ant  is 
found  belonging  to  the  genus  Liometopum.    The  same  species 
was  likewise  supposed  to  inhabit  California,  but  Professor 
Wheeler  J   found   that   although   the   two    forms    are   very 
closely  related,  the  American  differs  slightly  in  shape  and 
even  in  its  habits  from  the  European  species.    Whereas  the 
former  constructs  its  nests  underground,  the  latter  utilises 
for  that  purpose  the  abandoned  burrows  of  beetles  under  the 
bark  of  trees.    Hence  he  calls  the  American  ant,  Liometopum 
apiculatum.      It   is    limited  in  its  range  to  California  and 
Mexico.    Only  two  other  species  of  Liometopum  are  known. 
One,  (L.  microcephalum),  as  I  mentioned,  lives  in  southern 
Europe,  the  other  (L.  lindgreeni)  in  Assam.    It  is  not  often 
that  we  actually  become  acquainted  with  the  extinct  ancestors 
of  such  interesting  invertebrates  as  these.   But  fossil  forms 
of  Liometopum  have  been  discovered,  according  to  Dr.  Hand- 
lirsch§  in  the  Lower  Miocene  of  Croatia  and  the  Oligocene  of 
Colorado.    Even  in  Tertiary  times  the  genus  seems  to  have 
occupied  much  the  same  localities  as  it  does  to-day ;   it  only 
spread  formerly  further  north    no  doubt  owing  to  the  more 
favourable  climatic  conditions  then  prevailing. 

Many  other  similar  instances  might  be  quoted.  I  will  only 
allude  to  one  more.  The  two  well-known  European  ants 
Formica  cinerea  and  Formica  rufibarbis  had  been  reported 
from  the  south-western  States  of  North  America,  but  Pro- 
fessor Emery  doubted  the  correctness  of  the  identification 
until  Professor  Wheeler  sent  him  American  specimens.  Both 

*  Emery,  C.,  "  Nordamerikanische  Ameisenfauna,"  p.  299. 
t  Wheeler,  W.  M.,  "Honey  Ants,"  p.  347. 
J  Wheeler,  W.  M.,  "  North  American  Liometopum,"  p.  321. 
§  Handlirsch,  A.,  "  Die  Fossilen  Insekten,"  p.  870. 


EUEOPEAN   ANTS   IN   CALIFORNIA  217 

species  must  have  been  established  in  America  for  long  periods 
past,  as  their  range  extends  inland  in  a  north-eastward  direc- 
tion beyond  the  Rocky  Mountains. 

Instances  of  specific  identity  in  the  two  widely  separated 
regions  of  California  and  southern  Europe  are  to  be  found 
in  .several  groups.  Professor  Kraepelin  *  reports,  for  example, 
that  the  scolopendrid  Theatops  erythrocephalus  is  such  a 
case.  From  California  it  has  spread  as  far  as  Oregon. 
In  southern  Europe  it  is  known  from  Portugal,  Italy, 
Dalmatia  and  Hungary.  The  genus  Theak>ps  is  confined  to 
North  America,  including  the  Sandwich  islands,  and  southern 
Europe. 

A  member  of  the  order  Palpigradi,  a  minute  creature 
somewhat  resembling  a  scorpion  in  shape,  has  been  observed 
in  Texas  and  named  Koenenia  wheeleri  after  Professor 
Wheeler.  Two  other  members  of  the  genus  are  known  from 
South  America,  one  from  Chile,  the  other  from  Paraguay. 
But  the  nearest  relations  of  the  North  American  form  ar,e  evi- 
dently Koenenia  mirabilis  of  Sicily  and  Tunis,  and  K.  draco  of 
the  Balearic  islands.  The  only  two  other  species  live  in  Siam.f 
We  thus  have  in  this  ancient  group  again  the  same  intimate 
affinity  between  southern  Europe  and  south-western  North 
America  as  in  some  ants,  beetles  and  butterflies,  showing 
clearly  that  the  same  potent  cause,  which  is  certainly  not  acci- 
dental distribution,  has  contributed  to  bring  it  about.  In 
order,  however,  to  make  quite  sure  that  these  are  genuine 
instances  of  migration  on  a  land  surface,  and  not  due  to 
occasional  or  accidental  transport,  let  us  now  examine  care- 
fully the  range  of  a  large  fresh-water  form  and  endeavour  to 
trace  its  origin. 

Fresh-water  crayfishes,  as  Dr.  Ortmann  remarks  in  his 

excellent  account  of  them,  do  not  possess  any  exceptional 

means  of  dispersal.     They  are  restricted  to  fresh  water  and 

cannot  exist  out  of  it,  neither  in  salt  water  nor  on  land. 

Moreover,  they  do  not  possess,  during  any  stage  of  their  life 

history,  means  or  devices  which  might  favour  their  passive 

transport  from  one  fresh -water  system  to  another.  The  whole 

character  of  their  range  is  opposed  to  the  assumption  that 

*  Kraepelin,  K.,  "  Revision  der  Scolopendriden,"  pp.  64—66. 

t  Hansen,  H.  J.,  "On  Koenenia." 


218  OKIGIN   OF   LIFE   IN  AMEEICA 

their  dispersal  has  been  caused  by  any  exceptional  or  abnormal 
means  of  transport.  Few  zoologists  will  consequently  dis- 
agree with  Dr.  Ortmann's  *  assertion  that  fresh-water  cray- 
fishes are  among  the  most  important  animals  in  so  far  as  the 
study  of  their  distribution  elucidates  past  changes  of  land 
and  water  over  the  globe.  The  crayfishes  have  been  brought 
into  great  prominence  by  Professor  Huxley's  well-known 
treatise  on  the  subject.  More  recently  it  is  principally  in 
America  that  their  structure  and  distribution  have  been 
studied  with  great  assiduity.  Dr.  Faxon  f  was  the  first  to 
recognise  that  besides  the  American  genera  Potamobius 
(Astacus)  and  Cambarus,  there  is  a  third  genus  of  fresh- 
water crayfishes  which  inhabits  north -eastern  Asia.  The 
latter,  it  is  true,  is  only  'considered  a  sub-genus  of  Pota- 
mobius by  Dr.  Faxon  and  also  by  Dr.  Ortmann,  but,  as 
Mr.  Stebbing  J  has  pointed  out,  its  intermediate  position 
between  Potamobius  and  Cambarus  entitles  it  tp  rank  as  the 
distinct  genus  Cambaroides. 

The  geographical  distribution  of  these  crayfishes  (Pota- 
mobiidae)  is  very  suggestive  and  interesting.  Europe  is  the 
headquarters  of  the  old  and  well-known  genus  Astacus,  which 
name,  in  the  unfortunate  search  for  priority,  has  had  to 
give  way  to  Potamobius.  The  genus  ranges  practically 
throughout  Europe,  from  north  to  south  and  from  east  to 
west,  and  only  very  little  beyond  it.  Beyond  the  Caucasus 
it  crosses  into  Transcaucasia,  Turkestan  and  western  Siberia. 
It  is  quite  unkno.wn  in  the  remainder  of  Asia.  In  the  rivers 
of  eastern  Asia,  in  Korea,  Japan  and  eastern  Siberia  we  meet 
only  with  members  of  the  small  group  Cambaroides  referred 
to.  The  somewhat  close  resemblance  of  this  Asiatic  genus 
to  the  American  Cambarus  does  not  point  to  blood  relation- 
ship, according  to  Dr.  Ortmann,  merely  to  convergence.  In 
America  .we  find  not  only  Cambarus,  but  also  Potamobius,  the 
European  crayfish,  the  latter  genus  being  in  America  entirely 
confined  to  the  western  States.  Professor  Huxley  and  Dr. 
Faxon  both  urged  that  the  American  species  of  Potamobius  re- 
sembled the  European  crayfishes  much  more  than  the  Asiatic 

*  Ortmann,  A.  E., "  Distribution  of  Freshwater  Decapods,"  pp.  315—316. 
f  Faxon,  W.,  "Revision  of  Astacidae." 
J  Stebbing,  T.  E.  E.,  "  Crustacea,"  p.  208. 


CEAYFISHES  IN  THE   SOUTH-WEST          219 

ones,  yet,  like  Dr.  Ortmann,  they  maintained  that  Europe  was 
supplied  with  its  crayfish  fauna  from  the  East.  In  his  lucid 
essay  on  this  subject,  Dr.  Ortmann  argues  that  a  primitive 
group  of  Potamobiidae,  ancestral  to  all  the  living  ones,  must 
formerly  have  existed  in  eastern  Asia,  which  region  should 
be  regarded  as  the  centre  of  dispersal  of  the  family.  This 
ancient  group,  he  thinks,  sent  one  branch  westward  to  Europe 
and  another  eastward  across  the  old  Bering  Strait  land  bridge 
to  western  North  America.  Thus,  three  centres  of  dispersal 
gradually  originated1  in  which  the  old  stock  developed  on 
independent  lines.  The  middle  one  changed  to  Cambaroides, 
jvhile  the  two  branches  retained  the  ancient  characters.  From 
the  American  branch  eventually  originated  Cambarus,  which 
spread  eastward  into  the  eastern  States  of  North  America 
(see  pp.  289—91). 

I  accepted  Dr.  Ortmann 's  explanation  in  my  work  on  Euro- 
pean animals  as  an  hypothesis,  which  satisfactorily  accounted 
for  the  present  distribution  of  the  Potamobiidae.  Doubts, 
however,  have  since  arisen  in  my  mind  as  to  whether  there 
is  not  a  better  theory.  The  more  I  studied  the  problem  the 
less  I  felt  disposed  to  agree  with  Dr.  Ortmann's  explanation. 
Why  should  the  old  stock,  for  instance,  have  become  modified 
into  Cambaroides  in  its  original  centre  of  dispersal,  while  still 
flourishing  in  two  centres  enormously  distant  from  one 
another  ?  And  these  two  new  centres  were  reached  after  many 
struggles  and  vicissitudes,  after  long  and  weary  travels,  prob- 
ably through  hundreds  of  miles  of  unsuitable  ground.  One 
would  imagine  the  two  distant  branches  to  have  become 
more  and  more  unlike  one  another.  Five  species  of  the 
old  .stock  Potamobius  still  inhabit  the  streams  of  western 
America,  from  California  in  the  south  to  Alaska  in  the  north. 
If  Dr.  Ortmann's  theory  were  the  correct  one,  the  centre  of 
dispersal  of  the  more  modern  genus  Cambarus,  which  has 
developed  from  some  member  of  the  old  stock,  ought  to  be  in 
north-western  America.  Everything,  nevertheless,  points  to 
the  conclusion  that  the  new  genus  Cambarus  originated  in 
Mexico,  and  Dr.  Ortmann  (p.  291)  is  of  that  opinion,  having 
recently  supported  it  by  means  of  many  additional  facts  of 
distribution.* 

*  Ortmann,  A.  E.,  "Affinities  of  Cambarus." 


ORIGIN   OF   LIFE   IN   AMERICA 

It  is  to  south-western  North  America,  therefore,  that  we 
must  look  for  the  original  home  of  the  ancestral  group  of 
Potamobius.  They  still  inhabit  that  area,  and  may  have 
ispread  from  there  northward  to  Alaska,  and  even  further 
to  north-eastern  Asia,  eventually  giving  rise  to  Cambaroides. 
Taking  these  and  many  other  remarkable  facts  of  dis- 
tribution into  consideration,  it  appears  to  me  quite  pos- 
sible that  the  presence  of  the  crayfish  Potamobius  in 
Europe  and  North  America,  and  its  occurrence  in  the 
western  parts  only  of  the  latter  continent,  may  be  due  to 
an  ancient  land  connection  which,  as  already  suggested, 
joined  western  Europe  and  Mexico  by  way  of  the  West  Indies. 
Whether  the  family  originated  in  North  America  or  in  Europe 
will  have  to  form  the  subject  for  future  researches.  That  this 
migration  took  place  in  very  remote  times,  is  implied  by  the 
fact  that  Cambarus  primaevus  (which  Dr.  Faxon  believes  to 
be  a  Potamobius),  occurs  in  the  Eocene  beds  of  western 
Wyoming.  If  such  a  land  bridge  as  that  alluded  to  actually 
existed  in  early  Tertiary  or  late  Mesozoic  times,  it  may  be 
asked  why  do  we  not  meet  with  any  members  of  the  genus 
Potamobius  in  the  streams  of  the  West  Indian  islands  ?  To 
this  we  may  answer  that  geologists  are  practically  agreed 
that  in  post- Eocene,  or  even  during  Eocene  times,  the  whole 
area  of  the  Antilles  was  greatly  submerged,  so  that  we  may 
suppose  that  the  ancient  fauna  that  wandered  across  that  area 
from  either  Europe  or  North  America  was  largely  extermi- 
nated. That  the  islands  were  subsequently  again  connected 
with  the  mainland  we  may  assume  from  the  presence  of 
Cambarus  cubensis,  a  crayfish  peculiar  to  the  island  of  Cuba. 

My  views  as  to  the  nature  and  extent  of  that  mid-Atlantic 
land  bridge  will  be  more  fully  explained  in  the  chapter  dealing 
with  the  West  Indies.  The  presence  or  absence  of  such  a  land 
connection,  however,  is  of  such  vital  importance  to  the  eluci- 
dation of  the  phenomena  of  distribution,  that  I  may  he  ex- 
cused for  quoting  still  further  examples  of  animals  whose 
range  throws  light  on  the  solution  of  this  problem. 

In  the  beginning  of  this  chapter  (p.  205)  I  mentioned  the 
fact  that  the  spade-foot  toads  (Scaphiopus)  have  their  head- 
quarters in  Mexico  and  the  south-western  States  of  North 
America,  and  that  their  nearest  relations  are  the  members 


FAUNISTIC   PROBLEMS  221 

of  the  genus  Pelobates  which  inhabit  Europe.  Only  a 
single  species  (P.  syriacus)  has  been  discovered  in  Asia 
Minor.  The  others  extend  from  western  Europe  to  the 
Caspian.  Another  genus  (Pelodytes)  of  the  family  Pelo- 
batidae  has  one  species  in  Portugal  and  a  second  in  the 
Caucasus.  All  the  other  genera  of  the  family  are  found  in 
the  East,  and  are  more  remotely  akin  to  Scaphiopus  than 
Pelobates  is.  Hence  we  may  conclude  that  the  distribution 
of  these  two  genera  is  distinctly  favourable  to  the  suggested 
trans -Atlantic  land  bridge. 

Another  interesting  amphibian  that  I  have  alluded'  to 
(p.  137)  is  the  newt  Spelerpes,  which,  with  the  exception  of 
a  single  European  species,  is  peculiar  to  America  (see  Fig.  8). 
The  centre  of  dispersal  certainly  lies  in  Mexico,  from  which 
country  various  sections  have  spread  northward  into  the 
States,  southward  as  far  as  Peru,  and  eastward  to  the  island  of 
Haiti.  That  this  discontinuous  distribution  could  not  have 
been  brought  about  under  existing  geographical  conditions  is 
evident,  nevertheless,  since  no  fossil  Spelerpes  are  known,  we 
can  only  judge  of  the  age  of  the  genus  from  its  distribution. 
Dr.  Gadow  *  suggests  the  Oligocene  Period,  and  thinks  that  a 
north -Atlantic  land  connection,  such  as  the  one  I  have  de- 
scribed in  the  first  chapter  of  this  work,  from  Labrador  to 
Scotland  via  Greenland,  might  have  brought  about  the  exist- 
ing range  of  Spelerpes.  Since  the  single  European  species 
inhabits  only  Sardinia  and1  the  mountains  bordering  the  Gulf 
of  Genoa,  while  most  suitable  ground  for  its  existence  is  found 
further  north,  I  cannot  admit  that  Spelerpes  fuscus  reached 
Europe  in  that  manner.  The  land  bridge  by  which  it  crossed 
the  Atlantic  must  have  lain  much  further  south. 

I  have  already  alluded  to  the  fact  (p.  173),  that  there 
is  apparently  a  south-western  and  a  south-eastern  form 
of  the  American  glass  snake  (Ophisaurus  ventralis),  and 
that  both  of  them  extend  northward  for  considerable  dis- 
tances. The  only  other  members  of  the  genus  are  the 
European  glass  snake  (Ophisaurus  apus),  which  inhabits  the 
Mediterranean  region  and  is  very  like  the  American,  and  the 
Asiatic  species,  which  is  found  from  the  eastern  Himalayas 
to  Burma. 

*  Gadow,  H.,  "  Mexican  Amphibians  and  Eeptiles,"  p.  2-44. 


222  OKIGIN   OF  LIFE   IN   AMERICA 

Dr.  Buthven's  valuable  researches  into  the  origin  and  dis- 
tribution of  the  garter-snakes  (Thamnophis  =  Eutenia)  have 
been  discussed  in  an  earlier  chapter  (p.  128).  I  need  only 
restate  that  he  traces  the  home  of  the  genus  to  northern 
Mexico.  And  Thamnophis  is  clearly  an  of  shoot  from  the 
older  water-snakes  (Tropidonotus),  which  have  almost  a 
world -wide  range.  As  in  the  case  of  Potamobius  and 
Cambarus,  both  genera  seem  to  have  spread  northward 
from  their  south-western  centre,  the  south-western  Tropi- 
donotus validus  having  its  nearest  relation  in  the  Sar- 
dinian Tropidonotus  viperinus.  Dr.  Brown  *  recognised  per- 
fectly that  the  affinity  between  such  forms  as  the  European 
and  American  species  of  Tropidonotus  necessitated  the  exist- 
ence of  a  former  land  bridge  between  the  two  continents. 
He  also  urged  that  the  existence  of  this  bridge  must  have 
coincided  with  a  warm  climate  in  the  north,  for  he  naturally 
assumed  that  only  in  the  extreme  north  could  there  have  been 
such  a  land  connection.  Its  geological  age  he  fixes  at  about 
the  early  Miocene,  though  he  believes  many  of  the  present 
genera  to  have  been  in  existence  even  in  Eocene  times. 
My  objection  to  Dr.  Brown's  theory  is  that  we  Tiave  no  evi- 
dence in  Europe  of  a  southward  advance  of  Tropidonotus 
from  a  former  northern  centre  of  distribution,  nor  are  the 
northern  species  in  both  continents  more  closely  related  to 
one  another  than  the  southern  species.  The  former  existence 
of  a  more  southern  trans -Atlantic  land  bridge  in  early 
Tertiary  times,  on  the  other  hand,  is  supported,  by  such  a 
number  of  palaeontological  facts,  as  we  shall  learn  later  on, 
that  the  evidence  is  overwhelmingly  in  its  favour. 

It  is  quite  possible  that  the  western  tortoise  Clemmys 
marmorata,  or  its  ancestors,  for  the  genus,  as  I  mentioned 
(p.  133),  has  inhabited  south-western  North  America  since 
Eocene  times,  has  spread  across  the  same  mid- Atlantic  land 
bridge  to  western  Europe,  a  near  relation  (Clemmys  leprosa) 
being  peculiar  to  Portugal,  Spain  and  north-western  Africa. 

That  all  these  animals  living  in  south-western  North 
America  and  western  Europe  which  show  close  relationship, 
are  relicts  of  very  remote  geological  times  is  rendered  prob- 

*  Brown,  A.  E.,  "  Post-Glacial  Nearctic  Centres,"  p.  466. 


MAMMALIAN  AFFINITIES  223 

able,  partly  from  palaeontological  evidence,  and  partly  from 
other  methods  of  reasoning.  That  most  of  them  trace  their 
origin  in  America  or  Europe  to  the  former  existence  of  a 
direct  land  bridge  across  the  mid-Atlantic  seems  also  obvious. 
Yet  many  geologists  are  very  strongly  opposed  to  a  theo- 
retical bridging  of  the  Atlantic.  Nothing  short  of  a  well- 
marked  mammalian  affinity  between  the  two  areas  alluded  to 
will  satisfy  them.  We  can  produce  little  of  such  evidence,  be- 
cause most  groups  of  mammals  have  changed  very  rapidly 
during  the  course  of  the  Tertiary  Era.  A  few,  howev;er, 
such  as  the  rodents,  appear  to  have  the  faculty  of  preserving 
their  ancestral  characters  for  longer  periods,  and  some, 
apparently,  have  undergone  little  change  since  remote  times. 

There  are  two  instances,  one  among  the  voles,  the  other 
among  the  hare  family,  that  seem  to  point  to  the  existence  of 
the  land  connection  just  discussed,  and  these  cases  may  pos- 
sibly throw  more  light  on  the  age  of  the  land  bridge  than  the 
invertebrates  or  reptiles  can  do.  Professor  Tullberg  *  con- 
tends that  the  meadow  voles  (Arvicola— Microtus)  only  entered 
Europe  in  Pliocene  times  from  Asia,  where  they  had  already 
existed  for  some  time  previously.  He  also  expressed  the 
opinion  that  these  voles  subsequently  crossed  over  to  America 
from  Europe  by  a  north- Atlantic  land  connection,  which  I 
presume  must  be  the  Scotland-Greenland-Labrador  bridge. 
We  know  very  little  of  fossil  meadow  voles.  If  Professor 
Sehlosser  is  correct  in  his  assertion  that  only  geological  re- 
searches can  give  us  any  clues  as  to  former  changes  of 
land  and  water,  and  that  zoogeography  cannot  do  so,  the 
meadow  voles  can  teach  us  very  little. 

Yet  if  we  examine  the  present  range  of  one  of  the  sub- 
genera  of  meadow  voles,  such  as  Pitymys,  we  find  it  very 
remarkable  and  instructive.  One  species  lives  on  the  Mont 
d'Or  in  France,  at  a  height  of  over  4,000  feet,  another  on  one 
of  the  southern  Alpine  spurs,  at  a  height  of  6,000  feet.  De 
Selys  long  ago  described  a  species  (Pitymys  incertus)  from 
the  St.  Gothard  mountain,  a  locality  which  is  over  7,000 
feet  high ;  another  related  form  inhabits  the  Pic  du  Midi  in 
the  Pyrenees,  and  still  another  a  mountain  in  Sicily.  Quite 

*  Tullberg,  T.,  "  System  der  Nagetiere,"  p.  499. 


224  ORIGIN   OF  LIFE   IN   AMERICA 

a  number  of  species  are  now  known  from  southern  Spain  and 
Portugal,  owing  to  the  researches  of  Mr.  Thomas,  Mr.  Miller 
and  Dr.  Forsyth  Major.  To  judge  from  its  recent  distribu- 
tion, these  voles  of  the  sub-genus  or  genus  Pitymys  ought 
to  be  of  very  great  antiquity,  yet  not  a  single  fossil  specimen 
has  ever  been  found.  The  most  remarkable  fact  in  the  dis- 
tribution of  Pitymys  is  that  it  is  entirely  confined  to  Europe 
in  the  Old  World,  whereas  across  the  Atlantic,  in  Mexico, 
we  again  meet  with  a  member  of  this  group  known  as  the 
Jalapa  meadow  vole  (Pitymys  quasitor).  It  lives  there  at  an 
altitude  of  about  5,000  feet.  Only  two  other  species  are 
known  from  North  America,  one  (P.  nemoralis)  from  the 
Boston  Mountains  in  the  Indian  Territory,  the  other  from 
certain  areas  in  the  eastern  States.  The  latter  (P.  pine- 
torum)  occurs  from  southern  Florida  to  Carolina,  a  variety 
of  it  on  the  Allegheny  Mountains,  and  another  from  Long 
Island  to  the  borders  of  Illinois.  The  range  of  the  three 
American  species  is  disconnected,  and  confined  to  Mexico  and 
the  United  States.  What  is  the  relationship  of  these  species 
to  one  another,  and  which  is  the  oldest,  will  have  to  be  deter- 
mined by  future  researches,  also  whether  the  extinct  species 
discovered  in  Pennsylvania  by  Professor  Cope  really  belongs 
to  Pitymys  or  Microtus  proper.  At  any  rate,  there  is  nothing 
in  the  range  of  Pitymys  that  might  lead  us  to  suspect  that  it 
entered  North  America  from  the  north-west,  no  member  of 
the  group  having  as  yet  been  found  in  any  part  of  Canada  or 
Alaska.  In  Europe  Pitymys  is  unknown  in  the  north-west, 
whereas  a  number  of  species  inhabit  the  south-west.  Henoe 
the  American  group  of  Pitymys  may  possibly  have  been  de- 
rived from  one  or  more  species  which  crossed  the  Atlantic 
on  the  land  connection  above  referred  to. 

The  hare  family  (Leporidae),  as  a  whole,  has  a  very  wide 
distribution  in  Europe,  Asia,  Africa  and  America,  but  some 
of  the  sub-genera,  which  are  gradually  being  raised  to  the 
higher  dignity  of  genera,  are  confined  within  certain  circum- 
scribed limits.  In  his  study  on  the  recent  and  fossil  Lago- 
morpha,  Dr.  Forsyth  Major  *  comes  to  the  conclusion  that  this 
family  might  conveniently  be  divided,  according  to  the  osteo- 

*  Major,  Forsyth,  "  Fossil  and  recent  Lagomorpha,"  pp.  514 — 515. 


AMERICAN   RABBITS  225 

logical  characters  of  its  members,  into  two  groups,  viz.,  the 
Caprolagus  and  Lepus  groups.  The  first  of  these,  which  is  of 
particular  interest,  contains  the  four  genera  Caprolagus,  Neso- 
lagus,  Oryctolagus  and  Sylvilagus.  Caprolagus  lives  in  Asia, 
and  is  likewise  represented  in  European  Pliocene  beds.  The 
second  is  peculiar  to  the  island  of  Sumatra.  The  third,  which 
includes  the  European  rabbit,  has  an  extremely  discontinuous 
range,  being  confined,  according  to  Dr.  Major,  to  the  Mediter- 
ranean Region,  Western  Europe  and  South  Africa.  Sylvi- 
lagus is  peculiar  to  America.  From  its  very  scattered  range 
the  Caprolagus  group  of  hares  and  rabbits  would  seem  to 
be  of  ancient  lineage.  In  a  more  recent  study  of  the  hares  and 
their  allies,  Dr.  Lyon  recognised  nine  genera  of  this  group. 
He  separates  the  South  African  form  of  rabbit  from  the 
European,  raises  several  of  Dr.  Forsyth  Major's  sub-genera 
to  'the  rank  of  genera,  and  adds  the  new  genus  Pentalagus 
from  the  Liu  Kiu  islands  near  Japan.  Whereas  Dr.  Forsyth 
Major  recognised  four  sub-genera  of  the  American  Sylvi- 
lagus, Dr.  Lyon  places  only  two  sub-genera  under  this  genus. 
Although  Dr.  Lyon  gives  a  fuller  and  more  complete 
account  of  all  parts  of  the  skeleton  in  the  different  species  of 
Leporidae  than  Dr.  Forsyth  Major.  He  was  moreover  able  to 
detect  certain  prominent  structural  characters,  which  appar- 
ently escaped  Dr.  Major's  notice.  While  the  latter  believed 
in  the  close  relationship  of  the  European  and  the  Cape  rabbits, 
Dr.  Lyon  *  demonstrates  that  the  nearest  relation  of  the 
former  is  the  American  Sylvilagus.  The  skulls  of  the  two 
genera,  taken  as  a  whole,  are  not  markedly  different,  and  the 
teeth  are  essentially  alike. 

The  European  rabbit  also  possesses  marked  affinities  with 
Limnolagus,  another  American  genus  of  rabbits,  but  not  with 
any  of  the  Old  World  genera  of  the  family.  The  genus 
Oryctolagus,  with  its  single  species  the  European  rabbit 
(0.  cuniculus)  is  confined  to  the  countries  round  the  Medi- 
terranean. Only  in  France,  that  is  to  say,  in  western  Europe, 
is  there  a  tendency  to  a  northward  extension  of  this  range, 
and  in  that  it  resembles  a  great  many  other  typically  Medi- 
terranean animals.  Its  relation,  Sylvilagus,  ranges  from  the 

*  Lyon,  M.  W.,  "  The  Hares  and  their  Allies,"  p.  406. 
L.A.  Q 


226  ORIGIN   OF   LIFE   IN   AMERICA 

northern  border  of  the  United  States,  all  over  the  States 
and  Central  America.  In  South  America  its  exact  distribu- 
tion is  still  unknown,  but  it  possibly  reaches  Patagonia.  The 
cotton-tails  and  brush  rabbits  (Limnolagus)  occur  only  in 
the  southern  States.  We  thus  note  the  remarkable  fact 
that  rabbits  of  close  relationship  are  separated  in  one 
direction  by  a  comparatively  short  intervening  space  of  sea 
water,  in  the  other  by  a  very  much  longer  area  of  almost 
uninterrupted  land,  which  is  tenanted  almost  exclusively  by 
the  more  distantly  related  hares.  The  other  American 
rabbits,  the  pigmy  rabbit  (Brachylagus),  and  the  Popocatepetl 
rabbit  (Romerolagus),  are  confined  to  Mexico  and  western 
North  America.  The  south-western  region  must,  therefore, 
be  looked  upon  as  the  centre  of  dispersal  of  the  rabbits.* 

The  fossil  history  of  the  American  Leporidae  is  meagre  in 
the  .extreme.  Only  a  few  Oligocene  species  of  the  extinct 
Palaeolagus  are  known,  and  these,  according  to  Dr.  Major, 
seem  to  be  ancestral  to  the  modern  genus  Lepus.  No  fore- 
runner of  the  existing  Sylvilagus  and  Oryctolagus  has  yet  been 
found.  It  possibly  lived  in  south-western  North  America 
in  early  Tertiary  times.  Palaeolagus  already  possesses  in- 
cisors of  the  modern  type,  and  Dr.  Matthew  thinks  that  we 
may  look  among  Eocene  rodents,  or  even  in  the  fauna  of 
Cretaceous  deposits,  for  guidance  as  to  the  manner  of  evolu- 
tion of  the  teeth  of  the  Lagomorpiha-f 

This  leads  us  back  once  more  to  the  general  consideration 
of  the  American  Tertiary  deposits  and  the  affinities  of  their 
fauna.  These  deposits,  above  all,  ought  to  yield  indications 
as  to  whether  there  was  a  direct  land  connection  between 
south-western  North  America  and  western  Europe  across  the 
mid-Atlantic,  such  as  the  one  I  advocated. 

We  are  confronted  in  America  by  two  grand  problems, 
says  Professor  Osborn,J  one  being  the  chronological  correla- 
tion of  the  purely  fresh -water  horizons  with  one  another,  the 
other  the  chronological  correlation  of  American  horizons  with 
Eurasiatic  vertebrate  horizons.  When  these  are  worked  out, 
continues  the  same  writer,  we  shall  be  able  to  establish  a 

*  Nelson,  E.  W.,  "  Eabbits  of  North  America." 

t  Matthew,  W.  D.,  "  A  Horned  Eodent  from  Colorado,"  p.  307. 

t  Osborn,  H.  F.,  "  Cenozoic  Mammal  Horizons,"  pp.  29—30. 


ON   ATLANTIC   LAND   BRIDGES  227 

complete  and  very  accurate  geological  time  scale  for  the  entire 
Tertiary  Era,  and  to  speak  with  precision  regarding  the  time 
of  successive  migrations.  Much  still  remains  to  be  done  to 
establish  the  approximate  ages  of  the  various  Tertiary  de- 
posits in  Europe  and  America  before  we  can  definitely  say 
whether  a  certain  group  of  mammals  made  its  first  appearance 
in  Europe  or  in  America.  Possibly  we  may  not  reach  such 
a  state  of  knowledge  for  a  long  time  to  come. 

In  New  Mexico  what  are  known  as  the  "  Puerco  "  and  the 
"  Torrejon  "  formations  have  yielded  remains  of  archaic 
mammals,  some  of  which  are  related  to  mammals  occurring 
in  late  Mesozoic  or  early  Tertiary  deposits  of  Patagonia,  others 
indicating  affinity  with  those  of  a  similar  age  in  France. 
Now,  as  Professor  Deperet  tells  us,  it  is  inadmissible  to  argue 
that  mammals  so  nearly  akin  to  each  other  could  have  arisen 
independently  in  three  distinct  centres,  in  Patagonia,  in 
south-western  North  America  and  in  France.  We  can  only 
explain  these  palaeontological  affinities  by  migrations  from 
one  area  to  the  other.  Professor  Deperet  *  believes  that  the 
cradle  of  these  early  placental  mammals  was  in  North 
America,  and  that  they  crossed  over  to  Europe  by  utilising 
the  "  territories  of  the  North  Atlantic  which  had  risen  from 
the  sea."  This  is  a  somewhat  vague  statement,  yet  it  indi- 
cates clearly  that  the  great  French  palaeontologist  had  in  his 
mind  the  existence,  in  these  remote  geological  times,  of  some 
kind  of  north  Atlantic  land  bridge.  He  does  not  explain  how 
the  North  American  mammals  reached  Patagonia,  but  Pro- 
fessor Osborn  f  speaks  distinctly  of  a,  contemporary,  that  is 
to  say,  early  Eocene  or  previous  (Cretaceous)  land  connection 
between  North  America  and  South  America,  and  he  actually 
places  it  in  the  same  position  as  it  occupies  at  present  (see 
Fig.  21).  I  propose  to  discuss  it  later  on.  At  present  we  may 
confine  ourselves  strictly  to  the  European  affinities  of  North 
America. 

A  momentous  change  occurs,  according  to  Professor 
Osborn,  in  the  succeeding  Wasatch  formation  of  New  Mexico 
and  Wyoming.  The  parallelism  of  similar  stages  in  the 
archaic  mammals  of  western  Europe  and  south-western 

*  Deperet,  C.,  "Transformations  of  the  Animal  World,"  pp.  308—309. 
f  Osborn,  H.  F.,  "  Cenozoin  Mammal  Horizons,"  p.  33. 

Q2 


228  ORIGIN   OF   LIFE   IN   AMERICA 

North  America  remains  as  before.  The  new  feature  is  the 
sudden  appearance  of  true  carnivores,  ungulates,  primates 
and  rodents.  I  have  already  referred  to  Eohippus 
(p.  147)  as  an  early  representative  of  the  hoirke  family. 
Another  modem  family  which  traces  its  origin  back  to 
these  remote  times  is  that  of  the  tapirs,  for  the  Eocene 
Systemodon  has  all  the  characters  peculiar  to  the  recent 
Tapiridae.  Whether  the  early  primates  were  lemurs  or  true 
monkeys  is  as  yet  undecided.  The  rodents  all  belong  to  the 
extinct  Ischyromyidae,  which  Dr.  Matthew  *  believes  to 
have  been  arboreal  creatures,  somewhat  resembling  squirrels 
in  shape,  although  more  nearly  related  to  the  peculiar  and 
typically  west  American  sewellel  (Aplodontia). 

This  sudden  and  simultaneous  appearance  of  modern 
families  of  mammals,  along  with  several  extinct  ones,  in 
western  Europe  and  south-western  North  America  is  very 
striking,  and  has  to  be  accounted  for.  To  begin  with,  we 
have  to  determine  the  origin,  or  original  centre  of  dispersal 
of  this  fauna.  Professor  Osborn  feels  certain  that  this  fauna 
originated  neither  in  Africa  nor  in  South  America.  There 
remain,  he  thinks,  four  possible  sources.  They  may  have 
come  from  the  Great  Plains  Region  of  North  America,  from 
the  more  northerly  American  Mountain  Region,  from  the 
northerly  Eurasiatic  Region,  or  from  the  American-Asiatic 
land -mass.  He  is  in  favour  of  the  last  theory,  namely,  that 
of  the  intermediate  or  North  American -Asiatic  source  of 
this  fauna.  Still  he  believes  that  the  actual  origin  of  this 
modernised  fauna  will  not  be  determined  until  Eocene  fossil 
mammal  beds  in  the  northern  portions  of  America  and  Asia 
shall  have  been  discovered.  Such  beds  have  not  yet  been  met 
with,  nor  is  there  any  reason  to  suppose  that  they  will  be. 
Have  we  any  geological  evidence  for  the  supposition  that 
there  actually  existed  any  such  large  and  intimately  connected 
northern  land-mass  at  this  stage  of  the  geological  history  of 
the  earth  as  Professor  Osborn  f  implies  ?  No  doubt  it  is 
generally  assumed  that  Alaska  and  north-eastern  Asia  were 
joined  by  land  in  Eocene  times,  and  Professor  Schuchert,J 

*  Matthew,  W.  D.,  "  Osteology  of  Paramys,"  pp.  64—69. 
t  Osborn,  H.  F.,  "  Cenozoic  Mammal  Horizons,"  pp.  35 — 36. 
J  Schuchert,  C.,  "  Paleogeography  of  North  America,"  Plan  96. 


EAELY   TERTIARY  MAMMALS  229 

in  his  palaeontological  maps,  unites  America  in  this  manner 
with  Asia,  and  by  way  of  Greenland  with  Europe.  But  Pro- 
fessor Suess  contends  that,  although  these  affinities  in  the 
Eocene  faunas  of  America  and  Europe  imply  united  conti- 
nents in  the  north,  this  land  connection  was  probably  not  in 
the  vicinity  of  Bering  Sea.  On  the  contrary,  he  .rather  favours 
a  more  direct  land  bridge  between  North  America  and 
Europe.* 

During  the  latter  stages  of  the  Eocene  Period,  while  the 
Wind  River,  Bridger  and  Uinta  beds  were  being  laid  down, 
the    descendants    of   the    archaic   and    of    the    modernised 
mammals  gradually  evolved,  and  we  may  suppose  that  the 
archaic  mammals  finally  succumbed  in  the  struggle  for  exis- 
tence.    At  any  rate,  they  slowly  disappeared,  and  during 
the  process  of  their  elimination,  the  fauna  of  America  assumed 
a  more  independent  aspect,  the  affinities  with  Europe  becom- 
ing less  pronounced.    This  need  not  necessarily  imply  a  cessa- 
tion of  the  intimate  geographical  relationship  between  the  two 
continents.     The  growth  of  an  impenetrable  forest,  like  that 
in  the  interior  of  Brazil,  the  development  of  local  desert 
conditions,  or  the  existence  of   temporary   volcanic   distur- 
bances on  the  supposed  trans-Atlantic  land  connection,  would 
have  been  sufficient  to  faunistically  isolate  the  two  continents 
from  one  another.     In  the  succeeding  period,  the  Oligocene, 
the    faunal    resemblance    of    western    North    America    and 
western  Europe  once  more  became  conspicuous.     The  land 
area  available  for  the  development  of  mammalian  life  cer- 
tainly increased  in  America  during  early  Tertiary  times,  while 
a  corresponding  decrease  may  have  taken  place  on  the  trans  - 
Atlantic  land  connection,  thus  bringing  a  renewed  influx  of 
strange  forms  to  the  New  World.    Professor  Osborn  f  tells  us 
that  in  the  White  River,  John  Day  and  other  American  Oligo- 
cene formations,  sixteen  new  families  of  mammals  made  their 
appearance,   most  of  them  still  existing,    and   that   a  very 
similar  modernisation  occurred  in  western  Europe.    Six  new 
families  appear,  apparently  simultaneously,  in  both  areas.    It 
is  worthy  of  note  that  the  opossu'm  family  (Didelphyidae)  and 
the  rhinoceroses  (Rhinocerotidae)  now  make  their  first  entry 

*  Suess,  E.,  "  Antlitz  der  Erde,"  Vol.  III.2,  pp.  764—765. 
f  Osborn,  H.  F.,  "  Cenozoic  Mammal  Horizons,"  pp.  58 — 59. 


230  ORIGIN   OF   LIFE  IN   AMERICA 

into  North  America^  while  the  monkeys  (Primates)  disappear 
for  ever  from  the  continent. 

In  his  restoration  of  Oligocene  conditions  in  North 
America,  Professor  Schuchert  still  depicts  North  America 
as  being  joined  in  the  far  north  by  wide  land  bridges  with 
Asia  and  Europe,  while  practically  submerging  the  whole  of 
the  West  Indies.  As  we  shall  learn  later  on,  an  intimate 
relationship  exists  between  the  shallow  water  marine  forms 
of  early  Tertiary  European  and  Antillean  deposits,  and  this 
has  given  rise  to  the  suggestion  that  a  land  bridge  must  then 
have  united  Europe  and  the  Antilles.  If  'my  view  should  be 
substantiated,  that  the  resemblance  in  the  Oligocene  faunas  of 
Europe  and  south-western  North  America  is  due  to  the  exis- 
tence in  Oligocene  times  of  a  mid-Atlantic  land  bridge,  the 
West  Indian  area,  of  course,  could  not  have  been  submerged 
at  that  time. 

After  a  short  phase  of  independent  evolution,  during  which 
the  Oligocene  deposits  of  western  North  America  insensibly 
pass  into  Miocene  ones,  the  succeeding  Middle  Miocene  beds 
are  characterised  by  the  appearance  of  a  large  number  of  new 
forms,  among  which  the  elephants  (Proboscidea)  deserve 
special  mention.  Some  of  these  new  immigrants  are,  ap- 
parently, of  African,  others  of  Eurasiatic  origin.  The 
Miocene  beds  of  Europe  and  of  America  are  remarkable  for 
the  similarity  of  their  fauna.  The  conclusion  deduced  from 
this  fact  by  Professor  Osborn  *  is  that  the  North  American 
middle  Miocene  formations  contain  animals  which  first  appear 
in  the  lower  Miocene  of  Europe,  just  as  the  American  lower 
Miocene  contains  animals  that  first  appear  in  the  upper 
Oligocene  of  Europe. 

Now  it  is  quite  possible  that  while  the  faunistic  inter- 
change between  western  Europe  and  western  North  America 
took  place  by  means  of  one  land  connection  during  early 
Tertiary  times,  this  land  bridge  was  replaced  later  on  by  an 
entirely  different  one.  Professor  Deperet  f  had  some  such 
idea  in  his  mind  in  expressing  the  view  that  the  Miocene  and 
Pliocene  migrations  from  Europe  to  America  probably 
arrived  by  way  of  Asia  and  the  Bering  Strait,  while  the  earlier 

*  Osborn,  H.  F.,  "Cenozoic  Mammal  Horizons,"  p.  76. 

t  Dep6ret,  C.,  "Transformations  of  the  Animal  World,"  p.  314. 


CONCLUSIONS  231 

ones  came  direct  from  Europe.  Professor  Suess,*  on  the 
other  hand,  favours  a  north  Atlantic  land  connection  in  high 
latitudes  between  Greenland,  Iceland  and  Scotland,  and  he 
thinks  its  origin  dates  back  to  the  beginning  of  the  Miocene 
period.  Considering  that  there  is  such  unanimity  in  favour 
of  some  kind  of  land  bridge  between  the  Old  World  and  the 
New  at  this  time,  it  is  strange  that  Professor  Schuchert  f 
should  entirely  isolate  North  America  in  his  palaeogeographi- 
cal  maps  from  the  Old  World,  not  only  in  Miocene,  but  even 
in  Pliocene  times. 

Although  the  Pliocene  fauna,  according  to  Professor 
Osborn  (p.  81),  is  as  yet  only  imperfectly  and  sparsely 
known,  being  characterised  by  hosts  of  southern  invaders 
which  now  flood  the  continent,  a  direct  land  bridge  between 
North  America  and  the  Eurasiatic  continent  must  likewise 
have  existed,  unless  we  assume  that  the  mighty  elephant 
Tetrabelodon  (Dibelodon)  which  is  represented  by  several 
species  in  the  New  World,  reached  North  America  by  way 
of  South  America.  Whether  the  still  existing  more  hardy 
stock  of  Asiatic  immigrants  came  to  North  America  towards 
the  end  of  Pliocene,  as  I  argued  in  a  previous  chapter 
(p.  97),  or  during  Pleistocene  times,  is  a  question  which  had 
not  hitherto,  I  think,  been  seriously  debated.  That  their  pre- 
sence in  North  America  is  due  to  a  wide  land  bridge  across 
Bering  Strait  (see  Fig.  7)  seems  to  me  evident. 

In  this  very  brief  survey  of  the  past  faunas  of  NortH 
America  I  have  endeavoured  to  show  that  an  important  centre 
of  evolution  and  dispersal  existed  in  western  North  America 
in  the  past,  just  as  it  exists  to  a  lesser  degree  at  the  present 
day.  The  strong  faunistic  affinity  between  western  North 
America  and  western  Europe,  which  we  can  still  trace  at  this 
moment  among  many  of  the  invertebrates  and  lower  verte- 
brates of  the  two  areas,  seems  to  be  the  outcome  of  an  ancient 
direct  geographical  communion  between  these  land-masses. 
Certain  features  in  mammalian  palaeontology  appear  to 
strengthen  my  views,  which  are  primarily  based  on  a  study 
of  the  modern  fauna.  In  the  succeeding  chapters  I  shall 
bring  forward  further  evidence  showing  that  North  America 

*  Suess,  E.,  "  Antlitz  der  Erde,"  Vol.  III.2,  p.  765. 
t  Schuchert,  C.,  "  Paleogeography,"  PI.  98—100. 


232  OKIGIN   OF   LIFE   IN   AMEBICA 

and  Europe  were  joined  in  the  south,  while  northern,  Asia  was 
in  all  likelihood  disconnected  from  the  former.  The  principal 
point  which  I  think  has  been  clearly  demonstrated  is  that  the 
south-western  centre  of  dispersal  has  exerted  a  powerful  in- 
fluence on  the  development  of  the  living  faun,a  of  North 
America.  There  still  remains  one  other  feature  that  I  wish 
to  allude  to  before  concluding  this  chapter. 

I  have  mentioned  above  that,  while  eastern  Mexico  was 
either  wholly  or  partially  submerged  by  the  sea  during  later 
Mesozoic  and  early  Tertiary  times,  most  of  western  Mexico 
and  a  portion  of  the  Californian  coast  remained  dry  land,  as 
far  as  we  know,  all  through  geological  history.  It  ought  on 
that  account  to  be  a  preservation  ground  for  all  kinds  of 
relicts  of  bygone  ages.  And  so  it  is.  I  have  cited  a  number 
of  them  already,  although  the  country  can  scarcely  be  con- 
sidered as  being  exhaustively  explored.  The  fresh-water 
fishes  more  than  any  other  group  show  what  zoological  riches 
may  still  be  discovered  there.  The  Lerma  river  system,  for 
example,  in  south-western  Mexico  has  a  fish  fauna,  accord- 
ing to  Dr.  Meek,*  which  is  quite  as  distinct  and  character- 
istic as  if  it  were  on  an  island  in  the  sea.  Of  the  forty -nine 
species  of  fishes  now  known  to  occur  in  this  area,  not  a  single 
one  is  found  elsewhere.  These  forty-nine  species  belong  to 
seventeen  genera,  ten  of  them  being  quite  peculiar  to  this 
region.  This  result  is  all  the  more  surprising,  as  it  has  often 
been  argued,  by  advocates  of  accidental  introduction,  that  the 
eggs  of  fishes  are  apt  to  adhere  to  the  legs  or  feathers  of  water 
birds,  being  thus  easily  transported  to  other  river  systems 
or  isolated  lakes.  The  extremely  distinct  and  isolated 
character  of  the  Lerma  river  area  implies  that  dispersal  of 
fishes  is  not  affected  by  such  agencies  of  accidental  transport. 
Fishes  only  migrate  from  one  river  to  another  when  a  change 
of  drainage  occurs  in  the  head  waters,  or  when  the  stream 
itself  shifts  its  course. 

*  Meek,  S.  E.,  "  Fishes  of  Mexico,"  pp.  775—784." 


CHAPTEE    X 

THE    FAUNA    OF    CENTRAL    AMERICA 

THE  problems  presented  by  a  study  of  the  fauna  of  Central 
America  are  of  the  utmost  significance  in  our  investigations 
into  the  origin  of  the  American  fauna  as  a  whole.     Even 
the  casual  observer  cannot  fail  to  perceive  that  certain  animals 
from  each  of  the  two  great  continents  lying  to  the  north  and 
south  of  Central  America,  tend  to  spread  along  the  narrow 
isthmus,  and  thus  intermingle  with  one  another.    When  we 
look  at  Dr.  Wallace's  map  of  what  he  calls  the  "  Neotropical 
Region,"  and  notice  how  the  South    American    fauna   has 
apparently  invaded  the  whole  of  Central  America,  and  even 
crept  northward  along  the  lowlands  of  Mexico,  so  that  the 
triangular  table-land  of  that  country,  with  its  northern  in- 
habitants, looks  as  if  it  had  been  forced  like  a  wedge  between 
the  two  wings  of  the  southern  army  of  invaders,  the  whole 
•history  of  events  seems  to  be  clearly  unfolded  before  our  eyes. 
Apparently,  quite  a  simple  zoogeographical  problem,  and  one 
that  is  easily  soluble  by  a  study  of  the  distribution  of  existing 
animals.     Thus  it  seemed  to  Dr.  Wallace.    Of  the  geology  of 
Central  America  nothing  was    known    when  he  wrote    his 
famous  work  on  the  distribution  of  animals.     Nevertheless, 
he  argues  (pp.  10 — 13),  from  the  sudden  appearance  in  post- 
Tertiary    times    of    numerous    South    American    forms    of 
edentates  in  temperate  North  America,  and  from  such  facts 
as  the  occurrence  of  some  identical  species  of  sea  fish  on  the 
two  sides  of  the  Central  American  isthmus,  that  the  union 
of    North   and    South    America   must    be    a    comparatively 
recent  event,  and  that  these  continents  must  have  been  sepa- 
rated during  Miocene  and  Pliocene  times  by  a  wide  arm  of  the 
sea.    When  the  evidence  of  both  land  and  sea  animals  support 
each  other  as  they  do  here,  adds  Dr.  Wallace,*  the  conclusions 

*  Wallace,  A.  E.,  "  Distribution  of  Animals,"  Vol.  II.,  pp.  57—59. 


234  ORIGIN   OF   LIFE   IN   AMERICA 

arrived  at  are  almost  as  sure  as  if  we  had  geological  proof 
of  these  successive  subsidences.  The  author  of  the  "Geo- 
graphical Distribution  of  Animals  "  thus  not  only  claims  that 
zoogeography  is  of  great  value  as  an  interpreter  of  geological 
phenomena,  but  he  feels  confident  of  having  indicated  the 
correct  solution  to  the  problem  of  the  faunistic  relationship 
between  the  two  continents.  There  are  one  or  two  points, 
however,  in  the  fauna  of  South  and  Central  America,  which 
seem  to  throw  doubt  on  Dr.  Wallace's  interpretation  of  the 
facts  of  distribution.  He  states  (p.  58)  that  when  the  final 
union  of  the  two  continents  took  place,  the  tropical  climate 
of  the  lower  portion  of  Guatemala  and  Mexico  would  have 
invited  rapid  immigration  from  the  south,  while  some 
northern  forms  would  have  extended  their  range  into  and 
beyond  the  newly  elevated  territory.  That  the  fauna  of  South 
America  has  advanced  across  the  isthmus,  and  has  even  in- 
vaded the  State  of  Texas,  appears  probable  from  a  study  of 
the  existing  fauna.  We  need  not  even  cite  the  presence  of 
the  South  American  fossils  in  North  America  in  favour  of 
this  view.  All  sections,  indeed,  of  the  fauna  seem  to  have 
taken  part  in  this  northward  advance,  even  "the  fishes. 

Take  for  example  the  members  of  the  family  Cichlidae. 
Over  one  hundred  and  fifty  species  of  this  strictly  fresh- 
water group  are  known  from  America,  the  great  majority 
being  confined  to  South  America.  Mr.  Regan  *  is  of  opinion 
that  the  Central  American  and  Mexican  species  are  more 
specialized  than  the  South  American  ones,  and  that  the 
former  have  certainly  been  derived  from  the  latter.  No 
member  of  this  family  of  fishes  is  known  from  the  Mexican 
plateau,  and  only  three  or  four  species  extend  northward 
on  either  side  of  it,  North  America  being  almost  devoid 
of  Cichlidae  (see  Fig.  12).  All  the  available  evidence 
thus  points  to  South  America  as  the  place  of  origin  of  the 
family,  as  fax  as  the  New  World  is  concerned ;  and  thence  it 
has  spread  northward,  like  hosts  of  other  groups  of  animals. 
This  advance  must,  of  course,  have  taken  place  as  soon  as  a 
connected  land  passage  with  suitable  lakes  and  rivers  enabled 
them  to  proceed  northward.  Dr.  Wallace  thinks  that  the 
sudden  appearance  of  the  large  South  American  edentates 

*  Regan,  C.  Tate,  "  Fishes  of  Central  America,"  pp.  xiii-  xvi. 


-a 


FISHES  OF   CENTBAL  AMERICA  235 

in  North  America  occurred  in  post- Tertiary  times,  for  he 
believes  Central  America  to  have  been  still  submerged  during 
the  Pliocene  Period.  The  term  "  post-Tertiary,"  I  may  men- 
tion, is  synonymous  with  Quaternary  or  post-Pliocene.  Any 
geological  deposits  more  recent  than  Pliocene  come  within 
the  meaning  of  that  term.  But  the  skeletons  of  the  great 
South  American  M^lodon_and  Megalonyx  certainly  occur  in 
Texas  in  true  Pliocene  beds.  I  do  not  think  there  is  any  geo- 
logist in  America  now  who  would  uphold  the  Pleistocene,  or 
even  less  the  post-Glacial  age  of  these  deposits.  My  conten- 
tion, therefore,  is  that  the  northward  advance  from  South 
America  is  a  pre-Glacial  or  pre-Pleistocene  event. 

Now  one  of  the  most  remarkable  and  astonishing  features 
of  that  faunistically  so  peculiar  continent  of  South  America 
is  that,  whereas  its  tropical  fauna  has  very  little  affinity 
with  the  fauna  of  North  America,  the  more  remotely  placed 
Chilean  and  Patagonian  faunas  present  in  some  groups  of 
animals  a  striking  resemblance  to  it.  This  character  will  be 
more  fully  dealt  with  in  another  chapter  (pp.  410 — 419).  It 
may  be  mentioned,  however,  that  numerous  groups,  and  even 
species,  of  northern  plants  are  met  with  in  Chile,  which  are 
wholly,  or  almost  entirely,  absent  in  the  intervening  region, 
occupying  an  area  of  thousands  of  miles.  Northern  genera  of 
butterflies  and  beetles,  such  as  Argynnis,  Colias  and  Carabus, 
all  of  which  are  almost  unknown  in  the  countries  immediately 
south  of  Mexico,  reappear  in  numbers  in  the  extreme  southern 
tip  of  South  America.  Dr.  Wallace  thought  that  this  south- 
ward migration  of  northern  forms  of  animal  life  must  have 
been  effected  mainly  during  successive  Glacial  epochs,  when 
the  mountain-range  of  the  isthmus  of  Panama,  if  moderately 
increased  in  height,  might  have  become  adapted  for  the 
passage  of  northern  forms,  while  storms  might  often  have 
carried  insects  from  peak  to  peak,  over  intervening  forest 
lowlands,  or  narrow  straits  of  sea.  Dr.  Wallace's  idea  that  the 
mountains  all  along  Central  America  were  formerly  higher 
than  they  are  now  and  sustained  northern  forms  of  animal 
life  is  not  supported  by  any  evidence.  Considering  that  he 
imagined  the  long  isthmus  to  have  been  slowly  rising  from  the 
sea  since  pre-Glacial  times,  Dr.  Wallace's  suggestion  that 
the  mountains  were  so  much  higher  during  the  Glacial  Epoch 


236  OBIGIN   OF   LIFE   IN   AMEEICA 

than  they  are  now,  hardly  seems  well  founded.  Another  still 
stronger  objection  to  Dr.  Wallace's  *  theory  is  that  the 
northern  forms  alluded  to  as  occurring  in  Chile  and  Patagonia 
belong  almost  all  to  different  species,  sometimes  even  to  dif- 
ferent genera,  from  their  northern  relations.  If  storms  had 
anything  to  d'o  with  this  distribution  they  could  only  have 
acted  during  very  long  intervals  of  time  so  as  to  produce  such 
specific  and  generic  differences.  Moreover,  how  could  winds 
or  storms  affect  the  distribution  of  Carabus,  which  is  a  flight- 
less ground  insect  living  under  stones  ?  How  could  these 
agencies  have  transported  fresh-water  species  across  the  im- 
mense tropical  area,  for  several  Chilean  fresh -water  forms 
exhibit  a  similar  northern  affinity  ?  These  are  some  of  the 
problems  that  present  themselves  to  us.  There  are  numbers 
of  others.  Why  should  the  family  of  tortoises,  Dermate- 
mydidae,  which  is  known  to  have  inhabited  the  North 
American  continent  since  Cretaceous  times,  have  become  ex- 
tinct there  and  be  now  confined  to  Central  America  ? 

The  scarcity  of  land  and  fresh-water  fossils  in  Central 
America  obliges  us  to  resort  to  zoogeography  and  to  the  meagre 
geological  information  we  possess  in  elucidating  these  and 
other  problems.  Before  dealing  with  the  general  faunistic 
features  of  Central  America,  a  few  remarks  on  some  of  the 
more  important  geological  characters  will  be  of  interest. 

The  long  neck  of  Central  America  from  the  isthmus  of 
Tehuantepec  to  Panama,  which  joins  North  and  South 
America  to  one  another,  has  a  length  of  about  one  thousand 
five  hundred  miles.  We  are  sometimes  apt  to  forget  that  it 
does  not  lie  in  a  north  and  south  direction,  but  almost  east  and 
west.  Nearer  South  America  the  neck  of  land  starts  in  a 
due  westerly  direction  and  only  gradually  turns  somewhat 
towards  the  north  and  finally  north-westward.  Very  little  of 
this  immense  stretch  of  land  has  as  yet  been  geologically  sur- 
veyed. Nevertheless,  some  valuable  hints  as  to  its  geological 
history  have  been  gathered.  In  his  essay  on  the  geology  of 
the  isthmus  of  Panama,  Professor  Hill  f  tells  us  that,  pos- 
sibly before  the  vast  accumulations  of  more  modern  igneous 
and  sedimentary  rocks  of  Tertiary  and  post-Tertiary  age  were 

*  Wallace,  A.  &.,  "  Distribution  of  Animals,"  Vol.  II.,  p.  45. 
t  Hill,  R.  T.,  "Geological  History  of  Panama,"  pp.  241—257. 


GEOLOGY  OF  CENTEAL  AMEKICA     237 

laid  down,  a  foundation  of  granitic  rocks,  occurring  in  an  east 
and  west  arrangement,  existed  on  the  site  of  Central  America. 
Apparently  parallel  granitoid  ridges  extended  from  the  longi- 
tude of  Trinidad  directly  across  the  path  of  the  main  con- 
tinental trends  through  forty  degrees,  as  far  north  as  Acapulco 
in  Mexico.  These  fragmentary  data,' he  says,  are  sufficient  to 
indicate  that  in  pre-Tertiary  times  there  may  have  been  a 
basement  barrier  of  granitic  rocks  forming  an  oast  and  west 
arrangement  which  outlined  the  Central  American  region,  and 
constituted  an  ancient  buttress  against  or  upon  which  the 
higher  mountain  folding  has  originated.  Professor  Suess,* 
too,  speaks  of  the  mountain  chains  of  Yucatan  and  Guate- 
mala as  the  western  continuations  of  the  Antillean  system, 
contending  that  North  and  South  America  are  to  be  looked 
upon  as  two  radically  distinct  continents,  separated  from  one 
another  by  a  third  element,  that  of  Central  America  and  the 
Antilles.  All  this  agrees  to  some  extent,  as  we  shall  see  later 
on,  with  the  conclusions  we  can  draw  from  a  study  of  zoogeo- 
graphy. Central  America  and  the  Antilles,  which  are  collec- 
tively spoken  of  sometimes  as  the  remnants  of  an  ancient 
"  Antillean  Continent,"  possess  a  distinct  and  peculiar  fauna 
quite  apart  from  the  South  American  one  which  has  invaded 
this  area. 

Towards  the  end  of  the  Mesozoic  Era  parts  of  this  Antillean 
continent  must  have  begun  to  subside.  About  that  time  signs 
of  the  coming  volcanic  activity  appeared  all  along  the  Central 
American  region.  During  the  successive  igneous  eruptions  in 
early  Tertiary  times,  which  have  been  continued  with  varied 
intensity  to  the  present  day,  the  Atlantic  Ocean  seems  to  have 
invaded  the  existing  area  of  Central  America  and  submerged 
portions  of  it.  At  any  rate,  Professor  Hill  f  states  that 
biological  and  geological  evidence  led  him  to  the  con- 
clusion that  a  shallow  marine  transgression  must  have  existed 
somewhere  in  Central  America  during  Eocene  times,  although 
there  is  nothing  to  show  with  certainty  that  the  isthmus 
of  Panama  was  the  exact  site  of  this  inter-oceanic  con- 
nection. All  the  same,  Professor  Schuchert  J  seems  to  be 

*  Suess,  E.,  "  Antlitz  der  Erde,"  Vol.  I.,  p.  700. 

t  Hill,  E.  T.,  "  Geological  History  of  Panama,"  p.  265. 

{  Schuchert,  0.,  "  Paleogeography  of  North  America,"  pp.  96—97, 


238  OEIGIN   OF   LIFE   IN   AMERICA 

satisfied  that  the  isthmus  of  Panama  was  submerged  daring 
the  Eocene  Period,  and  that  the  submerged  area  of  Central 
America  greatly  increased  in  Oligocence  times.  Professor 
Hill,  who  has  dealt  with  various  lines  of  enquiry  in  regard  to 
the  geological  history  of  Central  America,  contends  that  they 
all  give  evidence  for  the  belief  that  no  connection  has  existed 
between  the  Pacific  and  Atlantic  Oceans  since  the  close  of  the 
Oligocene  (p.  270).  A  very  careful  re-examination  of  the 
fossils  of  Gatun,  near  the  Panama  Canal,  by  Professor  Toula, 
however,  throws  considerable  doubt  on  the  supposed  Eocene 
age  of  the  deposits  containing  these  fossils.  He  gives  reason 
for  his  belief  that  they  are  of  upper  Miocene,  possibly  even  of 
lower  Pliocene  age,  and  estimates  the  depth  of  water  of  the 
marine  channel  uniting  the  two  oceans  at  about  a  hundred  and 
fifty  feet.* 

In  conjunction  with  Dr.  Bose,  the  same  author  also  in- 
vestigated the  Tertiary  deposits  of  the  isthmus  of  Tehuantepeo 
in  southern  Mexico  with  very  noteworthy  results.  The  fossil 
mollusks  contained  in  them  indicate  that  the  sea  covered  the 
land  to  a  depth  of  from  fifty  to  two  hundred  fathoms,  that  is  to 
say  from  three  hundred  to  one  thousand  two  hundred  feet. 
As  the  isthmus  does  not  rise  much  beyond  eight  hundred 
feet,  the  existing  land,  even  as  far  north  as  this  region, 
was  submerged  by  a  shallow  sea.  Dr.  Bose  is  inclined  to  attri- 
bute to  this  fauna  an  early  Miocene  age,  while  Professor 
Toula  believes  it  to  be  younger,  in  fact  distinctly  "  jung- 
tertidr."-\ 

Now  it  has  been  argued,  and  the  argument  appears  most 
reasonable,  that  we  are  able  to  check  these  results  indicating 
a  submergence  of  parts  of  Central  America  by  means  of  two 
other  tests,  viz.,  the  distribution  of  living  animals  and  the 
palaeontology  of  North  America.  The  first  deals  mainly  with 
the  amount  of  affinity  existing  between  the  marine  animals 
of  the  Atlantic  and  Pacific  sides  of  Central  America.  From 
the  nearness  or  remoteness  in  relationship  of  the  species  on 
the  two  opposite  coasts  it  was  thought  we  might  determine  at 
what  particular  geological  period,  if  at  any,  the  Atlantic  and 
the  Pacific  Oceans  were  joined  to  one  another  across  Central 

*  Toula,  F.,  "  Jungtertiare  Fauna  von  Gatun,"  pp.  744—745. 

t  Bose,  E.,  and  F.  Toula,  "Fauna  von  Tehuantepec,"  pp.  221  and  273. 


ANCIENT   CENTRAL   AMEKICA  239 

America.  The  second  test  is  that  of  the  fossil  mammals  of 
North  America.  It  was  pointed  out  that,  as  no  trace  of  typi- 
cally South  American  species  occur  in  North  American  Oligo- 
cene  or  Miocene  deposits,  the  two  continents  must  have  been 
separated  by  a  sea  during  the  period  in  which  these  beds  were 
laid  down.  Let  us  examine  these  evidences  more  closely. 

A  good  many  writers  have  discussed  the  problem  of  the 
former  junction  of  the  Pacific  and  Atlantic  Oceans  across 
Central  America,  from  a  purely  biological  point  of  view.  Pro- 
fessor Gregory,*  who  last  summarised  the  subject,  came  to  the 
conclusion  that  the  waterway  across  Central  America  was 
finally  closed  in  the  Lower  Miocene,  or  possibly  even  in  the 
Upper  Oligocene.  Among  others  he  alluded  to  the  researches 
of  the  two  Agassiz,  father  and  son,  stating  that,  from  a  study 
of  the  sea-urchins,  they  proposed  to  date  the  junction  of  the 
two  oceans  much  further  back.  These  zoologists  referred  the 
separation  of  the  two  oceans  and  the  formation  of  the  Gulf 
Stream,  to  the  period  at  the  close  of  the  Cretaceous,  that  is  to 
say,  to  the  end  of  the  Secondary  Era.  Professor  Verrill  f 
finds  that  no  species  of  corals  are  identical  on  the  two  sides 
of  Central  America,  while  even  the  genera  and  families  show 
remarkable  contrasts.  The  numerous  genera  and  families  of 
reef -building  corals,  so  abundant  on  the  Atlantic  side,  are 
wholly  wanting  on  the  Pacific,  with  the  exception  of  Porites, 
which  is  represented  by  three  or  four  small  species. 

Mr.  Belt  J  maintained  that  the  marine  mollusks  on  the  two 
coasts  separated  by  the  narrow  isthmus  of  Darien  were  almost 
entirely  distinct.  So  remarkably  distinct  are  the  two  faunas, 
he  says,  that  most  zoologists  consider  that  there  has  been  no 
communication  in  the  tropics  between  the  Pacific  and  Atlantic 
Oceans  since  the  close  of  the  Miocene  Period.  An  apparently 
rather  remote  junction  of  the  two  oceans  is  suggested  by 
all  these  authors,  but  none  of  them  express  any  very  strong 
convictions  on  the  subject.  Dr.  Ortmann,  on  the  other  hand, 
states  that  the  affinities  of  the  Decapod  fauna  of  the  Atlantic 
and  Pacific  are  unmistakable,  and  that  we  have  ample  and  con- 
vincing evidence  of  a  former  connection  between  these  oceans. 

*  Gregory,  J.  W.,  "  Palaeontology  of  the  West  Indies,"  pp.  304—305. 
t  Verrill,  A.  E.,  "  Comparison  of  Coral  Faunae,"  p.  500. 
|  Belt,  Th.,  "  Naturalist  in  Nicaragua,"  p.  264. 


240  ORIGIN   OF   LIFE   IN   AMERICA 

Seven  species  of  crabs  and  their  allies  are  identical  to  the  two 
oceans,  while  many  others  are  closely  related.  The  fauna  as  a 
whole  implies  that  the  union  of  the  seas  cannot  have  been  of 
a  very  recent  date.  Accordingly  Dr.  Ortmann  *  is  of  opinion 
that  there  was  no  communication  since  Miocene  times. 

In  1880  Dr.  Gunther  f  declared  that  the  genera  of  fishes, 
with  scarcely  any  exception,  are  identical  on  the  two  sides 
of  Central  America.  Of  the  species  found  on  the  Pacific  side, 
nearly  one  half,  he  states,  have  proved  to  be  the  same  as  those 
of  the  Atlantic,  and  he  upholds  the  view  of  the  existence  o'f 
straits  and  channels  between  the  two  seas  until  a  geologically 
recent  period.  Since  Dr.  GunJther  expressed  these  views,  the 
fish  fauna  of  this  region  has  received  renewed  attention  and 
study,  over  a  thousand  species  now  being  known  from  the 
coasts  of  the  two  seas.  Of  this  large  number  only  seventy  - 
one  species,  or  six  per  cent.,  are  common  to  the  two  oceans, 
according  to  the  latest  researches  of  Professor  Jordan.  This 
great  discrepancy  between  Dr.  Giinther's  and  Professor 
Jordan's  results  arises,  of  course,  to  a  large  extent  from  the 
different  views  these  observers  hold  as  to  specific  limits. 
To  account  for  the  remarkable  identity  of  genera  and  the 
divergence  of  species,  Professor  Jordan  J  suggests  that  the 
isthmus  of  Panama  was  depressed  in  or  before  Miocene  times, 
that  the  channel  was  shallow,  and  that  the  currents  set  chiefly 
westward,  thus  favouring  the  transfer  of  Atlantic  rather  than 
Pacific  types.  In  the  case  of  the  Medusae,  the  affinity  between 
the  littoral  faunas  of  the  two  sides  of  Central  America  is 
much  closer  according  toDr.Bigelow§  than  in  the  higher  groups. 

It  has  been  suggested  by  Messrs.  Gill  and  Bransford  ||  that 
the  occurrence  of  marine  fishes  in  the  great  lake  of  Nicaragua 
is  to  be  looked  upon  as  an  indication  that  the  sea  once  flooded 
the  area  now  occupied  by  these  lakes.  That  these  fishes  are 
true  "  relicts  "  of  the  past,  representing  the  survivors  of  a 
marine  fauna,  has  recently  been  reaffirmed  by  Dr.  M'eek.^f 

*  Ortmann,  A.  E.,  "Distribution  of  Decapods,"  p.  398. 

t  Gunther,  A.,  "  Study  of  Fishes,"  p.  280. 

J  Jordan,  D.  S.,  "Study  of  Fishes,"  Vol.  I.,  pp.  272—280. 

§  Bigelow,  H.  B.,  "  Medusae,"  p.  228. 

||  Gill,  Th.,  and  J.  F.  Bransford,  "  Fishes  of  Lake  Nicaragua,"  p.  179. 

f  Meek,  S.  E.,  "  Fishes  of  Nicaragua,"  p.  99. 


AGE  OF  CENTRAL  AMERICA  241 

The  species  in  question  are,  in  the  first  instance,  two  sharks, 
viz.,  Carcharhinus  nicaraguensis  and  Pristis  antiquorum,  as 
well  as  Pomadasis  grandis  and  others  whose  ancestors  are 
marine  forms.  The  antiquity  of  the  region  is  indicated  by 
the  occurrence  both  in  Lake  Nicaragua  and  Lake  Managua 
of  the  Central  American  gar-pike  (Lepidosteus  tropicus). 

The  studies  of  geographical  distribution,  particularly  those 
of  marine  species,  have  thus  led  to  the  conclusion  that  tha 
Central  American  land  bridge  has  been  in  existence  certainly 
since  pre-Glacial  times.  No  zoologist  has  suggested  even  the 
possibility  of  a  submergence  of  Central  America  having  taken 
place  as  late  as  the  Pleistocene  Period.  No  biological  support 
can  be  given,  therefore,  to  the  theory  which  has  beien  advanced 
by  some  writers,  that  the  Glacial  Period  was  due  to  a  diversion 
of  the  Gulf  Stream  across  the  isthmus  of  Panama.  On  the 
other  hand,  Central  America  was  certainly  submerged  by  a 
shallow  sea  in  two  or  more  places  in  early  Pliocene  or  Miocene 
times.  Another  very  important  character,  which  is  revealed 
both  from  a  study  of  the  recent  and  fossil  marine  fauna,  is  the 
Atlantic  facies  of  the  animals.  The  movement  of  the  species 
seems  to  have  taken  place  from  the  West  Indian  area  towards 
the  Pacific  Ocean,  thus  implying  the  existence  of  a  strong 
current  in  that  direction.  Speaking  of  the  Tertiary  deposits 
of  Tehuantepec,  Dr.  Bose  *  remarks  that  the  main  mass  of  the 
species  contained  therein  are  related  to  Atlantic  forms.  Only 
very  few  show  affinities  with  Pacific  types.  Similar  views 
were  expressed  by  Professor  Jordan  and  Dr.  Ortmann  an 
regard  to  the  recent  marine  fauna. 

A  further  complication,  as  Professor  Gregory,  f  pointed 
out,  oremains  to  be  considered.  It  is  not  at  all  certain,  he 
thinks,  that  when  the  Isthmus  of  Panama  was  submerged 
there  was  free  communication  between  the  Atlantic  and  the 
Pacific  Oceans.  The  Caribbean  Sea,  he  argues,  may  then  have 
been  a  gulf  of  the  Pacific,  separated  from  the  Atlantic  by  the 
land  area  of  the  hypothetical  "  Antillia."  As  I  shall  show  in 
the  next  chapter,  which  deals  with  the  origin  of  the  West 
Indian  fauna,  the  Caribbean  Sea  could  not  have  been' .separated 
from  the  Atlantic  Ocean  at  so  late  a  geological  period  as  that 

*  Bose,  E.,  and  F.  Toula,  "  Fauna  von  Tehuantepec,"  p.  220. 
t  Gregory,  J.  W.,      Palaeontology  of  the  West  Indies,"  p.  305. 
L.A.  B 


242  ORIGIN  OF  LIFE  IN  AMERICA 

during  which  the  S6a  spread  across  Central  America.  The 
general  opinion  seems  to  be  that  the  submergence  of  Central 
America  was  due  to  extensive  subsidence  in  the  Caribbean 
area  and  likewise  in  the  Gulf  of  Mexico.  The  Mediterranean 
character  of  the  West  Indian  marine  fauna,  moreover,  implies 
the  probability  of  a  free  migration  from  the  one  area  to  the 
other  along  some  ancient  shore-line.  A  land  bridge  joining 
North  and  South  America  along  the  chain  of  the  Lesser 
Antilles,  alluded  to  by  Professor  Gregory,  may  possibly  have 
existed;  but  it  must,  I  think,  already  have  been  destroyed 
at  the  time  of  the  submergence  of  the  Isthmus  of  Panama. 
And  yet  I  concur  with  Professor  Gr.egory  in  thinking  that 
when  the  latter  was  submerged  there  need  not  necessarily 
have  been  free  communication  between  the  Atlantic  and  the 
Pacific  Oceans.  We  must  remember  that  all  efforts  have 
hitherto  failed  to  discover  any  traces  of  Tertiary  sediments  on 
the  sea-board  betweeoi  southern  Mexico  and  Panama.  This 
seems  to  imply  that  land  lay  to  the  west  of  Central  America, 
and  that  the  Pacific  Ocean  was  formerly  situated  further 
westward  than  at  present.  What  would  appear  as  connections 
between  the  two  oceans  may  have  been  merely  shallow  bays  in 
the  land  referred  to.  Certain  peninsulas  would  then  have 
projected  eastward  from  this  old  Pacific  land  towards  those 
parts  of  Central  America  that  were  then  in  existence  (see 
Fig.  16).  Without  giving  further  evidence,  these  theories 
may  appear  somewhat  visionary,  but  as  the  subject  will  be 
more  fully  discussed  later  on  (p.  408),  I  need  not  enlarge 
upon  it  at  present. 

A  comparison  of  the  marine  faunas  of  the  two  shores  of 
Central  America  does  not  yield  such  satisfactory  results  in 
establishing  the  geological  age  of  the  submergence,  because 
we  have  as  yet  little  idea  of  the  length  of  time  during  .which1 
animals  may  retain  their  specific  characters.  The  evidence 
derived  from  the  first  appearance  in  North  America  of  dis- 
tinctly South  American  mammals  would  seem  to  give  us  a 
better  clue  as  to  the  date  of  the  formation  of  the  present 
Central  American  land  bridge. 

This  appeal  to  the  past  dispersals  of  mammals  in  recon- 
structing former  conditions  of  land  and  water  has  been  utilised 
in  several  of  the  previous  chapters,  and  in  this  case  many  bio- 


HISTORY   OF   THE   MARINE  FAUNA  243 

legists  have  attested  their  strong  belief  in  the  validity  of  the 
argument.  A  very  early  Tertiary  or  late  Mesozoic  influx  of 
mammals  from  South  America  into  North  America  has  already 
been  alluded  to.  After  this  event  long  periods  of  time  elapsed, 
during  which  the  two  continents  were  seemingly  separated 
from  one  another.  Th,en  southern  mammals  once  more 
appeared  in  the  north.  This  later  invasion  is  proved  from 
the  contents  of  the  deposits  in  Texas.  Here  we  meet 
with  gravigrade  edentates,  and  these  deposits  have  now 
been  definitely  placed  by  Professor  Osborn  *  to  the  middle 
Pliocene.  Hence  Central  America  in  its  present  form  and 
shape  would  be  of  Pliocene  origin.  Although  Mr.  Lydekker  f 
places  this  event  at  the  end  of  the  Miocene  Period,  Professor 
Deperet  J  and  Dr.  Smith  Woodward  §  concur  in  the  opinion 
expressed  by  Professor  Osborn  which  is  in  conformity  with 
that  elicited  by  Professor  Toula.  The  latter  bases  his  evidence 
on  the  fossils  contained  in  th.e  Panama  and  Tehuantepec 
deposits. 

Since  the  testimony  derived  from  the  recent  marine  fauna 
also  agrees  fairly  well  with  the  above  conclusions,  it  seems 
reasonable  to  conclude  that  Central  America  in  its  present 
outlines,  forming  a  highway  for  intercommunication  between 
North  and  South  America,  came  into  existence  about  the 
beginning  of  the  Pliocene  Period.  Thus  one  of  the  problems 
alluded  to  at  the  beginning  of  the  chapter  is  apparently 
solved. 

Yet  still  another  difficulty  has  suddenly  arisen  owing  to 
the  recent  most  surprising  discovery  of  true  edentate  re- 
mains of  Megalonyx  type  in  the  Mascall  beds  of  Oregon, 
which  are  of  Middle  or  Lower  Miocene  age.||  If  the 
Gatun  deposits  near  Panama  are  really,  as  Professor  Toula 
affirms,  of  Upper  Miocene  age,  how  can  we  reconcile  the 
submergence  of  Panama,  and  probably  also  of  the  isthmus  of 
Tehuantepec,  with  this  latest  discovery  in  Oregon  ?  The  whole 
problem  is  evidently  much  more  complex  than  it  at  first  ap- 

*  Osborn,  H.  F.,  "  Cenozoic  Mammal  Horizons,"  p.  82. 

t  Lydekker,  E.,  "  History  of  Mammals,"  p.  119. 

|  Deperet,  0.,  "  Transformations  of  Animal  World,"  p.  282. 

§  Woodward,  A.  Smith,  "Palaeontology,"  p.  429. 

||   Osborn,  H.  F.,  "  Age  of  Mammals,"  p.  289, 


244  ORIGIN   OF  LIFE   IN   AMERICA 

peared.  In  the  Oligocene  deposits  of  the  northern  continent, 
as  above  mentioned,  there  are  no  distinctly  South  American 
species.  Yet,  curiously  enough,  when  we  come  to  still  earlier 
strata,  we  again  meet  with  remains  of  animals  that  exhibit 
characteristically  South  American  features.  In  the  Puerco 
formation,  in  north-western  New  Mexico,  a  number  of 
peculiar  mammalian  bones  have  been  discovered,  which  were 
referred  by  Professor  Cope  to  the  extinct  order  Tillodontia, 
whereas  Dr.  Wortman  endeavoured  to  show  that  Cope's 
genera  Psittacotherium,  Onychodectes  and  Conoryctes  were 
ancestral  to  the  Gravigrada  or  ground  sloths  of  South  America. 
Dr.  Wortman  *  proposed  that  they  be  placed  in  a  new  sub- 
order of  the  edentates,  which  he  named  Ganodonta.  But  he 
did  not  look  upon  these  animals  as  immigrants  from  South 
America.  He  thought  this  order  of  primitive  mammals  must 
have  actually  arisen  in  North  America,  and  have  thence  emi- 
grated to  South  America  before  the  close  of  the  Eocene 
Period.  Although  these  Ganodonta  are  no  longer  considered 
as  ancestral  to  the  ground  sloths,  the  same  Puerco  formation 
has  yielded  other  mammals  which  show  distinctly  South 
American  or  rather  Patagonian  affinities.  Dr.  Wortman's 
theory  as  to  the  North  American  origin  of  the  Ganodonta 
has  not  found  favour.  Dr.  Osborn,  in  fact,  urges  that  a 
direct  land  connection  with  South  America  is  indicated  at 
this  stage  of  geological  history  in  order  to  account  for  the 
South  American  features  in  the  North  American  fauna.  This 
view  has  been  amply  confirmed  by  the  remarkable  discovery  in 
Wyoming,  in  a  deposit  of  Middle  Eocene  age  (Bridger),  of 
the  remains  of  a  true  armadillo  closely  related  to  the  modern 
armadillos,  but  exhibiting  a  few  more  primitive  characters. f 

Since  Dr.  Ameghino's  researches  in  Patagonia  have  brought 
to  light  such  a  wealth  of  edentates  from  the  earliest 
Tertiary,  and  probably  even  from  Mesozoic  deposits,  scarcely 
anyone  can  doubt  that  South  America  is  the  original  home 
of  that  group  of  mammals,  and  that  they  have  passed  from 
there  during  the  Eocene  Period  and  earlier  into  North 
America,  and  not  vice  versa,  as  Dr.  Wortman  suggested. 
But  very  few  would  assert  that  the  physical  geography  of  the 

*  Wortman,  J.  L.,  "  Psittacotherium,"  pp.  259—262. 

i  Osborn,  H.  F.,  "  An  Armadillo  from  the  Eocene,"  p.  163. 


AFFINITIES   OF    NORTH   AND   SOUTH         245 

New  World  was  the  same  then  as  it  is  now,  and  that  Central 
and  South  America  had  already  been  evolved  in  anything  like 
the  present  outlines.  As  I  shall  endeavour  to  demonstrate 
later  on,  South  America  did  not  then  exist  as  a  distinct  great 
continent.  A  large  land-mass  evidently  lay  in  the  neigh- 
bourhood of  the  existing  State  of  Brazil  and  another  further 
south.  And  as  far  as  we  Imow,  the  southern  land-mass  was 
the  original  home  of  the  edentates.  Between  it  and  Central 
America  on  the  site  of  the  present  South  American  continent 
there  were  one  or  more  broad  marine  channels,  or  oceans,  as 
we  might  call  them.  And  yet  the  edentates  succeed cd  in 
attaining  North  America.  I  do  not  now  wish  to  discuss  my 
reasons  for  the  supposition  that  western  Mexico  was  then 
united  by  a  direct  land  bridge  with  Chile.  I  only  mention  it 
in  order  to  indicate  that  the  appearance  of  edentates  in  the 
Eocene  of  North  America  does  not  afford  a  proof  of  the  ex- 
istence of  Central  America  at  that  time,  nor  during  the 
Miocene  Period. 

Professor  Osborn,  as  I  mentioned  before,  indicates  the 
nature  of  the  land  connection  between  North  and  South 
America  in  the  dawn  of  the  Tertiary  Era  on  a  map  which  he 
kindly  allowed  me  to  copy  (Fig.  21).  However,  he  expresses 
the  belief  that  already  in  early  Eocene  times,  that  is  to  say 
almost  before  the  appearance  of  the  above-mentioned  arma- 
dillo in  North  America,  the  land  bridge  had  ceased  to  exist. 
We  are  too  apt,  I  think,  to  look  upon  South  America  as  exclu- 
sively the  home  of  edentates,  forgetting  that  many  other  mam- 
mals may  have  originated  there  too.  We  may  not  all  agree 
with  Dr.  Ameghino  *  in  attaching  the  importance  he  does 
to  that  continent  as  a  source  of  the  Tertiary  mammalia, 
but  I  believe  we  possess  other  evidences  of  a  faunistic  inter- 
change between  Chile  and  Patagonia  on  the  one  hand,  and 
western  North  America  on  the  other,  during  the  ages  that 
passed  between  the  Lower  Eocene  and  the  Miooene. 

In  southern  Africa  we  meet  with  a  group  of  small  blind 
subterranean  creatures,  the  golden  moles  (Chrysochloridae) 
which  are  among  the  most  primitive  mammals  in  existence. 
They  are  quite  confined  at  present  to  South  Africa.  But 

*  Ameghino,  Fl.  "  South  America,  the  Source  of  Mammalia." 


246  ORIGIN   OF   LIFE   IN   AMERICA 

within  recent  years  the  remains  of  a  small  insectivore  have 
been  met  with  in  the  early  Tertiary  Santa  Cruz  deposits  of 
Patagonia.  This  mammal,  according  to  Professor  Scott,*  is 
genetically  related  to  the  African  golden  moles.  The  South 
American  Necrolestes,  as  it  has  been  called,  is  certainly  more 
primitive  in  structure  than  its  African  relations.  Moreover, 
in  western  North  America  fossil  mammals  have  been  dis- 
covered both  in  Oligocene  and  Miocene  strata  which  have  been 
referred  to  the  same  family  Chrysochloridae.  It  is  true  that 
Dr.  Matthew  f  is  now  inclined  to  place  the  Oligocene  Apter- 
nodus  among  the  nearly  related  family  Centetidae,  but  the  two 
other  genera  Xenotherium  and  Arctoryctes  are  still  looked 
upon  as  true  chrysochlorids.  A  possible  land  connection 
between  Africa  and  South  America  will  be  discussed  later  on. 
Whether  Patagonia  was  the  original  home  of  the  chryso- 
chlorids or  South  Africa  we  cannot  tell,  but  the  family  may 
possibly  have  spread  from  South  America  to  North  America 
by  utilising  the  hypothetical  land  bridge  that  I  think  lay  to 
the  west  of  the  present  continent. 

A  few  words  of  appreciation  of  the  splendid  work  that  has 
been  done  in  making  us  acquainted  with  the  rich  fauna  and 
flora  of  Central  America  are  due  to  Mr.  Godman.  For  years 
he  and  Mr.  Salvin  laboured  with  great  industry  and  at  con- 
siderable expense  in  bringing  together  an  immense  collection 
of  vertebrates  and  invertebrates,  subsequently  publishing  th& 
series  of  beautifully  illustrated  volumes  of  the  "  Biologia 
Centrali- Americana  "  in  which  the  results  of  their  studies  were 
made  known  to  the  scientific  world.  In  the  volume  describing 
the  botany  of  Mexico  and  Central  America  there  is  an  excel- 
lent summary  dealing  with  the  constituents  of  the  flora  and 
their  relationships.  No  such  summary  has  been  attempted  in 
the  other  volumes,  so  that  Mr.  Hemsley's  account  of  the  plants 
of  Mexico  and  Central  America  is  of  particular  value  to  those 
who  are  engaged  in  a  study  of  the  zoogeography  of  that  region. 

The  first  item  of  interest  is  one  which  we  have  noticed 
occasionally  among  apparently  very  ancient  groups  of  North 
American  animals.  Genera  like  the  amphibians  Spelerpes 
and  Amblystoma,  which  have  their  headquarters  in  Mexico, 

*  Scott,  W.  B.,  "Eeport  of  Princeton  Expedition,"  Vol.  V. 
t  Matthew,  W.  D.,  "The  Skull  of  Apternodus,"  p.  35. 


FLORA   OF   CENTEAL  AMERICA  247 

are  either  absent  or  very  rare  in  the  western  United  States  of 
North  America,  while  abundant  in  the  eastern  States.  Some 
of  these  bear  an  impress  of  their  antiquity  in  their  wide  and 
discontinuous  range.  Now  Mr.  Hemsley  enumerates  the  fol- 
lowing genera  of  trees  as  occurring  in  southern  Mexico  and  in 
the  Atlantic  States  of  North  America,  though  they  are  absent 
from  the  Pacific  forests  of  the  western  United  States: 
Magnolia,  Asimina,  Tilia,  Bobinia,  Liquidambar,  Ilex,  Dio- 
spyros,  Bumelia,  Ulmus,  Celtis,  Morus,  Ostrya,  Carpinus  and 
Carya.  Even  species  of  plants  from  southern  Mexico  and  the 
Atlantic  States  of  North  America  are  sometimes  identical, 
such  as  Liquidambar  styraciflua,  Ostrya  virginica  and  Car- 
pinus americana.  And  yet  only  four  out  of  the  fourteen 
genera  referred  to  extend  even  to  northern  Mexico.  Of  some 
of  these  we  possess  fossil  evidence  that  they  lived  in  Europe 
already  in  early  Tertiary  times,  and  we  may  safely  assume  that 
the  whole  group  is  of  great  antiquity.  The  flora  of  Guatemala 
is  essentially  of  the  same  composition,  according  to  Mr. 
Hemsley,  as  that  of  southern  Mexico,  though  apparently  less 
rich  in  specific  diversity.  Some  of  the  trees  just  alluded 
to,  such  as  limes  (Tilia)  and  elms  (Ulmus),  are  unknown 
in  Guatemala;  others,  for  instance  sweet  gums  (Liqui- 
dambar), mulberries  (Morus),  lever-wood  (Ostrya)  and  horn- 
beams (Carpinus),  occur  in  that  country.  The  southern  floral 
province  of  Mr.  Hemsley  comprises  Nicaragua,  Costa  Bica 
and  Panama ;  and,  as  might  be  expected,  these  countries  ex- 
hibit a  much  closer  relationship  with  the  South  American 
tropical  flora  than  Guatemala  or  Mexico  do.  The  endemic 
generic  element  of  the  whole  of  Mexico  and  Central  America 
is  rather  inconspicuous,  but  the  southern  floral  province  is  by 
far  the  poorest  of  the  three  into  which  the  region  has  been 
divided.  One  of  the  most  curious  features  in  the  constitution 
of  the  flora  of  Mexico  is  one  which  I  have  already  briefly, 
referred  to,  namely,  the  presence  there  and  in  the  extreme 
south  of  South  America  of  certain  northern  genera  of  plants 
which  are  absent  or  only  represented  in  a  few  scattered  dis* 
tricts  in  the  intermediate  region.  Mr.  Hemsley  assumes  that 
such  plants  have  spread  southward  in  remote  times.  There 
are  likewise  genera  of  distinctly  southern  origin  with  a  simi- 
larly discontinuous  range  in  a  northward  direction.  I  need 


248  OKIGIN   OF   LIFE   IN   AMERICA 

only  mention  Fuchsia,  which  is  abundant  in  Chile  and  Pata- 
gonia, reappears  more  sparingly  in  Colombia,  and  is  almost 
unknown  further  north  until  we  come  to  Guatemala  and 
Mexico.  The  extreme  antiquity  of  this  genus  is  indicated 
by  its  occurrence  on  the  island  of  Haiti  (F.  triphylla),  while 
it  is  altogether  absent  from  the  rest  of  the  West  Indian 
Islands. 

In  his  analysis  of  the  flora  of  the  whole  region,  Mr. 
Hemsley  *  informs  us  that  the  northern  province,  that  is 
to  say  the  plateau  of  Mexico,  is  the  focus  of  a  xerophilous 
flora  extending  into  the  dry  regions  of  south  Mexico  and  into 
the  territories  north  of  Mexico.  The  central  province,  com- 
prising southern  Mexico  and  Guatemala,  possesses  a  mingling 
of  northern  and  southern  types  exhibiting  an  extraordinarily 
rich  production  of  local  species.  The  southern  province  is 
merely  an  outlier  of  the  American  tropical  flora.  The  tropical 
element  of  the  whole  flora  is  more  closely  allied  to  that  of 
eastern  South  America  than  to  that  of  the  West  Indies. 

The  relationship  of  the  Mexican  and  Central  American 
floras  to  those  of  other  parts  of  the  world  is  also  of  import- 
ance. Thus  Mexico  and  Central  America  have  a  large  number 
of  genera  in  common  with  eastern  Asia,  with  Africa,  Mada- 
gascar and  Europe.  They  likewise  exhibit  affinities  with  the 
Galapagos  islands,  with  New  Zealand,  Australia  and  Polynesia. 

Now,  if  we  compare  the  results  of  the  study  of  botany  with 
those  derived  from  an  examination  of  the  mammalian  fauna, 
we  are  struck  at  once  by  the  fact  that  the  plants  among  which 
the  mammals  live  must  be  of  much  greater  antiquity  than  the 
latter.  As  Mr.  Alston  f  tells  us,  the  mammals  of  Mexico 
and  Central  America  are  composed,  partly  of  southern  species 
not  found  southward  of  Mexico,  of  a  few  that  extend  as  far 
south  as  Panama,  and  chiefly  of  South  American  ones  which 
have  spread  across  Central  America.  There  are  also  a  number 
of  autochthonous  species  in  this  region.  Yet  very  few  of  the 
genera  are  found  in  other  parts  of  the  world  than  America. 

Among  our  new  acquaintances  we  meet  for  the  first  time 
with  the  kinkajous,  one  species  of  which  (Potos  flavus)  has 
succeeded  in  reaching  the  State  of  Vera  Cruz  in  Mexico. 

*  Hemsley,  W.  B.,  "  Botany  of  Central  America,"  pp.  306—315. 
t  Alston,  E.  R.,  "Mammals  of  Central  America." 


MONKEYS   AND   RACCOONS  249 

From  my  previous  remarks  (p.  152)  it  would  appear  as  if  the 
raccoon  family  (Procyonidae)  had  originated  in  some  western 
land  in  America,  and  yet  the  genus  Cercoleptes  (Potos),  which 
belongs  to  this  family,  is  certainly  an  invader  from  the  south. 
Indeed,  when  we  examine  the  range  of  the  members  of  this 
typically  American  family  of  Procyonidae,  we  notice  the 
peculiar  feature  that  almost  all  the  species  are  confined  to  the 
Pacific  coast.  The  raccoon  (Procyon  lotor)  no  doubt  has  ex- 
tended its  range  to  the  eastern  States,  while  the  allied  species 
Procyon  maynardi,  as  we  have  learnt,  is  even  confined  to  the 
Bahama  islands,  and  one,  the  coati  (Nasua  rufa),  has  a  wide 
distribution  in  South  America  from  Bolivia  eastward.  Almost 
all  the  other  members  of  the  family,  however,  inhabit 
curiously  disconnected  areas  in  the  vicinity  of  the  Pacific 
Ocean.  Bassaricyon  lives  in  Ecuador,  Panama  and  Costa 
Rica.  One  species  of  Bassariscus  is  peculiar  to  the  island 
of  Espiritu- Santo  near  lower  California,  another  ranges  from 
Mexico  to  the  western  States,  a  third  occurs  in  western 
Mexico,  Guatemala,  Costa  Rica  and  on  Mount  Chiriqui,  in 
western  Panama,  at  a  height  of  6,000  feet.  Of  the  coatis 
(Nasua),  one  species  passes  from  Mexico  northward  to  Cali- 
fornia and  southward  to  Costa  Rica,  another  is  confined  to 
the  island  of  Cozumel,  a  third  lives  in  the  Ecuador  mountains 
at  a  height  of  7,000  feet,  whereas  Nasua  olivacea  is  met 
with  in  Santa  Fe  de  Bogota  and  in  the  Merida  of  Venezuela 
at  heights  up  to  12,000  feet.  Altogether  it  looks  as  if  the 
members  of  the  family  Procyonidae  had  spread  from  various 
western  foci.  Some  of  them  may  have  retained  their  original 
distribution,  while  the  more  adaptable  genera  sent  outposts 
eastward  into  the  great  continents.  The  early  stages  of  this 
evolution  must  have  taken  place  before  either  Central  America 
or  South  America  had  become  consolidated  into  anything  like 
their  present  shapes.  Later  on  I  shall  have  occasion  to  dis- 
cuss other  similar  cases  of  discontinuous  distribution  occur- 
ring among  the  lower  vertebrates.  All  of  these  appear  to  be 
due  to  the  same  peculiar  features  in  the  physical  geography 
of  Tertiary  America. 

In  eastern  Mexico  we  make  our  first  acquaintance  with 
monkeys.  In  early  Eocene  times,  as  already  mentioned, 
monkeys,  belonging  to  extinct  groups,  probably  entered  the 


250  ORIGIN   OF   LIFE    IN   AMERICA 

United  States  from  the  south.  They  seem  to  have  had  a  short 
existence  in  North  America,  for  no  trace  of  them  has  been 
noticed  in  later  deposits.  Ever  since  renewed  facilities  for  a 
northward  advance  occurred  an  entirely  new  invasion  has 
taken  place,  and  one  of  the  "  howlers  "  can  now  be  heard  at 
night  even  in  the  forests  of  Vera  Cruz  in  eastern  Mexico.  A 
spider  monkey  ( Ateles  vellerosus)  may  be  seen  in  the,  same  dis- 
trict gracefully  swinging  from  branch  to  branch.  These 
monkeys  differ  in  distribution  from  the  raccoon  family  in  so 
far  as  they  have  their  centre  of  distribution  in  Brazil  and 
northern  South  America,  from  which  they  no  doubt  invaded 
Central  America  in  more  recent  geological  times.  There  are 
other  families  of  mammals  which  we  meet  here  for  the  first 
time.  We  need  not  dwell  on  them  any  longer,  as  we  shall 
have  occasion  to  become  acquainted  with  them  in  subsequent 
chapters. 

The  wealth  of  new  bird  life  in  Central  America  is  very 
striking,  and  is  vividly  described  'in  Mr.  Belt's  *  delightful 
book  of  travels  in  Nicaragua.  Among  the  more  noteworthy 
families  are  the  toucans (Rhamphastidae), with  their  enormous 
gaily-coloured  bills,  the  humming-birds  (Trochilidae),  a  great 
variety  of  parrots,  the  peculiar  curassows  and  many  others. 
Some  of  these  of  course,  like  the  humming-birds,  enteir  the 
United  States  largely  during  their  northward  migrations,  and 
to  some  extent  are  resident  in  the  southern  States.  I  should 
also  mention  the  most  beautiful  of  all  birds,  the  quesal 
(Trogon  resplendens),  or  royal  bird  of  the  Aztecs  as  it  has 
been  called,  with  its  delicately  tinted  plumage  of  metallic 
green  and  blue,  and  its  long  waving  plumes.  The  Trogonidae 
now  have  their  headquarters  in  Central  and  South  America, 
but  Trogon  gallicus  occurs  in  France  in  Miocene  deposits ; 
and  this  seems  to  suggest  in  what  manner  the  early  members 
of  the  family  crossed  over  to  Africa  and  the  Oriental  Region, 
where  some  genera  are  still  found  living ;  the  discontinuous 
range  corroborating  the  palaeontological  evidence  of  the  great 
antiquity  of  the  group.  As  Messrs.  Salvin  and  Godman  f 
remind  us,  the  avifauna  of  Central  America  is  essentially 

*  Belt,  J.,  "Naturalist  in  Nicaragua." 

t  Salvin,  0.,  and  F.  D.  Godman,  "  Birds  of  Mexico  and  Central 
America," 


BIRDS   OP   CENTRAL   AMERICA  251 

neotropical,  with  certain  peculiar  endemic  forms,  the  greater 
number  among  'the  latter  being  confined  to  Mexico  arid 
Guatemala. 

I  alluded  above  to  the  fact  that  the  family  of  tortoises, 
Dermatemydidae,  is  entirely  confined  to  Central  America. 
The  only  species  of  the  family  (Dermatemys  mawi)  inhabits 
precisely  that  part  of  Central  America  which  we  have  reason 
to  believe  to  be  one  of  its  oldest  parts,  viz.,  Guatemala  and  the 
neighbouring  Honduras  and  Yucatan.  Several  members  of 
the  family  formerly  lived  in  North  America.  They  first  ap- 
peared in  Cretaceous  times,  and  still  inhabited  the  south- 
western States  during  the  Eocene  Period.  It  is  possible  they 
may  then  have  spread  to  Guatemala,  becoming  subsequently 
extinct  in  their  centre  of  dispersal.*  Another  family  which 
I  mentioned  before  (p.  134),  the  "  snapping  turtles  "  (Cheli- 
dridae),  occur  in  eastern  North  America  from  Mexico  to 
Canada.  Southward  of  their  range  they  are  found  only  in 
Guatemala  and  Ecuador.  We  have  noted  examples  of  a 
similar  discontinuous  range  before.  Others  will  be  cited  in 
the  next  chapter. 

More  important  from  a  faunistic  point  of  view  are  such 
creatures,  as  for  instance  the  snake-like  limbless  amphibians, 
belonging  to  the  family  Coeciliidae.  They  live  in  moist  ground, 
and  lead  altogether  a  burrowing  life.  Their  distribution  ought 
to  give  us,  therefore,  some  valuable  hints  as  to  former  changes 
of  land  and  water.  Dr.  Sarasin  f  looks  upon  this  family  as  a 
pre-Cretaceous  relict,  on  account  of  its  peculiar  discontinuous 
range,  namely  India,  the  Seychelles,  east  Africa,  west  Africa, 
South  and  Central  America.  Whether  we  agree  With  him  or 
with  Dr.  Alcock,J  who  believes  that  the  family  wandered 
along  a  continuous  land  surface  from  India  across  Africa  to 
northern  South  America  in  early  Tertiary  times,  there  can  be 
no  doubt  at  all  as  to  these  subterranean  amphibians  being 
exceedingly  ancient.  The  American  home  of  this  circum- 
tropical  family,  as  Dr.  Gadow  §  points  out,  is  South  America. 
No  members  are  known  from  the  West  Indies  or  the  Galapagos 

*  Hay,  O.  P.,  "  On  Fossil  Turtles,"  p.  32. 

t  Sarasin,  F.,  "  Geschichte  d.  Tierwelt  von  Ceylon,"  pp.  74—76. 

t  Alcock,  A.,  "  Description  of  Apodous  Amphibian,"  p.  270. 

§  Gadow,  H.,  "  Distribution  of  Mexican  Amphibians,"  pp.  199—200. 


252  ORIGIN   OF   LIFE   IN   AMERICA 

islands.  Dr.  Gadow  next  proceeds  to  argue  that  because  one 
of  these  coecilians  inhabits  eastern  Mexico,  its  ancestors  must 
have  travelled  slowly  across  the  whole  neck  of  Central  America 
since  the  close  of  the  Miocene  Epoch,  when  he  assumes  the 
isthmus  to  have  been  first  opened  up  for  southern  immigrants. 
This  argument  is  in  so  far  faulty,  as  the  coecilians  need  not 
necessarily  have  passed  through  Central  America.  The  inti- 
mate relationship  that  exists  among  many  ancient  species  of 
Central  America  to  those  of  northern  South  America  suggests 
the  existence  of  some  far  older  link  between  these  countries. 
In  very  remote  times  species  were,  I  believe,  able  to  reach 
certain  areas  such  as  Guatemala  and  western  Mexico  long 
before  the  present  Central  America  had  com©  into  existence, 
that  is  to  say  long  before  Pliocene  times.  Dr.  Gadow  himself 
urged  that  the  Isthmus  of  Panama  is  but  the  last  vestige  of  a 
former  much  broader  land  connection  between  North  and 
South  America  (p.  243).  In  my  opinion  this  should  read 
"  the  Isthmus  of  Panama  contains  some  vestiges  of  a  former 
much  broader  land  connection." 

To  the  uninitiated  the  Typhlopidae  would  seem  nearly 
related  to  the  coecilians.  Both  are  snake-like  burrowing  crea- 
tures, and  yet  the  former  are  true  snakes  and,  therefore, 
reptiles,  while  the  others  are  merely  limbless  amphibians.  On 
close  examination  the  true  burrowing-snakes  (Typhlopidae) 
are  found  to  be  covered  with  minute  cycloid  scales,  and  to 
exhibit  other  reptilian  characters.  Their  distribution  is  ex- 
tremely discontinuous  and  extensive,  and  they  are  largely 
confined  to  solitary  islands.  That  they  possess  no  special 
facilities  for  accidental  dispersal  across  the  ocean  is  evident, 
and  yet  it  is  held  by  some  zoologists  that  their  presence  on 
islands,  such  as  Christmas  island  for  instance,  can  only  be 
due  to  such  a  cause.  A't  any  rate,  the  family  exhibits  all  the 
signs  of  antiquity,  and,  in  the  absence  of  any  positive  evidence 
of  accidentally  distributed  species,  I  am  firmly  convinced  that 
they  spread  by  the  usual  method  of  slow  migration  on  land. 
Dr.  Sarasin  *  places  the  dispersal  of  the  family  into  pre- 
Cretaceous  times,  in  spite  of  the  fact  that  we  possess  no 
palaeontological  evidence  of  their  antiquity.  All  the  same  he 

*  Sarasin,  F.,  "Tierwelt  von  Ceylon,"  p.  75. 


BURROWING   SNAKES  253 

is  perfectly  justified  in  doing  so,  because  it  can  be  shown  from 
various  other  tests  that  the  great  continents  must  have  been 
united  by  certain  land  connections,  and  that  the  present  dis- 
tribution of  the  Typhlopidae  can  be  readily  explained  if  we 
assume  that  their  dispersal  took  place  at  the  same  time.  The 
presence  of  Typhlops  tenuis  in  Guatemala  and  Mexico,  on  that 
account,  points  to  an  ancient  union  between  these  countries 
arid  to  a  survival  in  them  of  a  relict  fauna  during  a  long  course 
of  geological  ages,  in  which  the  two  countries  may  have  been 
separated. 

I  suggested  above  (p.  131)  that  the  rattlesnakes,  belong- 
ing to  the  genus  Crotalus,  were  of  early  Tertiary  origin. 
The  centre  of  dispersal  lies  in  the  south-western  States  of 
North  America,  all  the  species  except  one  being  confined 
to  that  continent.  The  black-tailed  rattlesnake  (Crotalus 
terrificus)  is  the  only  one  which,  according  to  Mr.  Boulenger,* 
ranges  from  south-western  North  America  to  South  America. 
Whether  the  South  American  species  is  identical  with  the 
North  American  one  is  a  matter  in  which  authorities  disagree. 
All  concur,  however,  in  the  view  that  the  genus  Crotalus 
reappears  in  South  America  in  one  or  more  forms,  differing 
but  slightly  from  those  inhabiting  Mexico.  And  these  South 
American  forms  are  not,  as  we  might  expect,  confined  to  the 
west  coast,  but  have  even  penetrated  to  eastern  Brazil,  if 
Mr.  Boulenger's  records  are  reliable.  At  the  same  time  it 
seems  as  if  their  range  in  South  America  was  very  discon- 
tinuous. 

The  fresh-water  fish  fauna  of  Central  America  is  described 
by  Professor  Eigenmann  f  as  poor,  the  genera  south  of  the 
Isthmus  of  Tehuantepec  being  practically  all  South  American. 
The  North  American  fauna  is  entirely  distinct  from  that  of 
tropical  America,  the  former  not  having  contributed  a  single 
element  to  the  fresh-water  fish  fauna  of  South  America.  It 
is  interesting  to  compare  this  view  with  those  founded  on 
other  fresh-water  groups  such  as  the  mollusks  and  crus- 
taceans. 


*  Boulenger,  G.  A.,  "Catalogue  of  Snakes,"  Vol.  III.,  p.  573. 
t  Eigenmann,  C.  H.,  "  Freshwater  Fishes  of  South  America,"  pp.  521 
—522. 


254  OBIGIN   OF   LIFE  IN   AMERICA 

I  suggested  above  (p.  161)  that  the  fresh- water  mussels 
(Unionidae)  probably  effected  their  principal  dispersal  during 
the  Mesozoic  Era,  and  that  this  circumstance  might  account 
for  the  fact  that  we  possess  distinct  proofs  of  a  migration  of 
species  from  North  to  South  America.  The  great  genus  Unio 
has  recently  been  subdivided  by  Dr.  Simpson  into  numerous 
genera.  One  group  of  Unio  (Plagiola),  ranging  from  Mexico 
to  the  Mississippi  drainage  "basin,  reappears  southward  in 
Nicaragua,  another  (Lampsilis)  is  known  from  Guatemala 
to  Yucatan.  Other  groups  of  Unio  are  confined  to  South 
America.  Unio-Tetraplodon  occurs  in  Ecuador,  having  spread 
from  there  into  the  Amazon  valley.  Unio-Castalina  lives  in 
southern  Brazil,  Unio-Castaliella  in  Surinam  and  so  forth. 
Finally  Unio-Diplodon  principally  inhabits  Chile,  Argentina 
and  Patagonia,  while  it  reappears  right  across  the  Pacific 
in  New  Zealand  and  Australia. 

The  range  of  these  groups  of  Unio  is  apparently  very  com- 
plex in  South  America.  'Nevertheless,  I  quite  concur  with  Dr. 
Simpson  *  in  the  belief  that  they  all  are  the  descendants  of 
certain  members  of  the  family  Unionidae,  which  wandered 
slowly  from  one  river  system  into  another,  during  the  Triassic 
or  some  later  Mesozoic  Period,  from  North  America  to  South 
America.  To  judge  from  the  general  distribution  of  the  Unio- 
nidae in  South  America,  they  entered  that  continent  from  the 
west  and  only  reached  the  eastern  States  subsequently.  The 
group  Unio-Hyria,  as  Dr.  von  Ihering  f  tells  us,  is  nothing 
but  a  modified  Unio,  which  has  comparatively  recently  pene- 
trated from  Guiana  into  Brazil.  The  most  surprising  fact 
which  is  so  strongly  brought  out  in  that  author's  remarkable 
researches  is,  that,  while  these  Unionidae  live  in  company  with 
other  families  of  fresh-water  mussels  in  eastern  South 
America,  in  Central  America,  Ecuador,  Peru  and  Chile,  that 
is  to  say  westward  of  the  Andes,  Unios  alone  occur.  This  con- 
firms the  opinion  I  expressed  several  times  in  previous  chap- 
ters, that  the  faunistic  interchange  between  North  and  South 
America  took  place  between  the  western  portions  of  the  two 
continents. 

*  Simpson,  C.  J.,  "Synopsis  of  the  Najades,"  p.  507. 

t  Ihering,  H.  von,  "  Archhelenis  und  Archinotis,"  p.  122. 


FRESHWATER  CRABS  255 

The  fresh-water  crabs  (Potamonidae)  must  have  invaded 
Central  America  from  the  south.  The  family  is  confined  to 
southern  Asia,  southern  Europe,  Africa,  South  and  Central 
America.  Except  for  a  few  species  in  Mexico,  fresh-water 
crabs  are  entirely  absent  from  North  America,  nor  do  we 
possess  any  evidence  of  their  ever  having  lived  there.*  A 
comparison  with  the  range  of  Unio  is,  therefore,  of  particular 
interest.  The  two  South  American  groups  of  fresh-water1 
crabs  apparently  spread  westward  from  eastern  South 
America,  that  is  to  say  in  a  direction  opposed  to  that  taken 
by  the  Unios.  We  need  only  consider  the  northern  group 
which,  to  judge  from  its  range,  is  much  the  oldest.  .'Dr. 
Ortmann  f  distinguishes  the  three  genera  Kingsleya,  Epilo- 
bocera  'and  Pseudothelphusa.  Kingsleya  only  occurs  in 
Guiana,  while  Epilobocera  is  peculiar  to  the  Greater 
Antilles.  The  third  genus,  Pseudothelphusa,  ranges  from 
the  Amazon  through  Guiana,  Venezuela  and  Colombia  north- 
ward as  far  as  Mexico,  and  south-westward  to  Ecuador,  Peru 
and  Bolivia.  There  are  quite  a  number  of  endemic  species  of 
fresh-water  crabs  in  Central  America.  Yet  are  we  to  conclude 
from  this  fact  that  a  slow  migration  took  place  across  the 
long  isthmus  since  Pliocene  times  ?  On  the  contrary,  if,  as 
Dr.  Ortmann  suggests,  th©  genus  Epilobocera  arose  in  the 
West  Indies  from  some  ancestral  Central  American  Pseudo- 
thelphusa, that  event  must  have  happened  in  much  more 
remote  times.  It  is  customary  to  assume  that  the  great  mass 
of  the  South  American  fauna,  including  mammals,  birds, 
reptiles,  fishes  and  invertebrates  all  surged  across  th©  newly 
opened  highway  towards  Mexico  in  the  Pliocene  Period.  If 
Epilobocera  succeeded  subsequently  in  crossing  from  Central 
America  on  a  land  bridge  to  Cuba,  Haiti  and  Portorico,  how 
can  we  account  for  the  fact  that  the  existing  faunas  of  Central 
America  and  the  Greater  Antilles  do  not  show  more  affinity 
to  one  another  than  they  actually  do  ?  As  compared  with 
Central  America  the  mammalian  fauna  of  the  West  Indies 
is  .strikingly  distinct  and  poor  in  species.  We  have  also  to 
take  into  consideration  that  certain  species  of  Pseudothelphusa 

*  Eathbun,  Mary  J.,  "  Freshwater  Crabs  of  America." 
t  Ortmann,  A.  E.,  "Distribution  of  Freshwater  Decapods,"  pp.  306 — 
309. 


256  ORIGIN  OF  LIFE  IN  AMERICA 

possess  a  remarkably  discontinuous  range.  Pseudothelphusa 
colombiana  inhabits  the  United  States  of  Colombia.  In  the 
extreme  western  end  of  Panama,  in  the  Chiriqui  region,  it 
occurs  at  a  height  of  4,000  feet,  and  a  thousand  miles  north 
of  this  locality  it  is  met  with  in  Mexico.  All  along  the  great 
isthmus,  on  the  -other  hand,  there  are  isolated  localities  in 
which  distinct  species  are  found.  Both  the  ranges  of  Unio 
and  Pseudothelphusa  in  Central  America  seem  to  me  more 
in  agreement  with  the  theory  of  the  existence  to  the  west  of 
Central  America  of  an  ancient  continuous  land  surface  uniting 
Colombia  and  certain  parts  only  of  Central  America,  while  the 
rest  of  the  latter  was  still  largely  submerged. 

One  of  the  chief  zoogeographical  features  in  the  range  of  the 
land  and  fresh-water  mollusks  of  Central  America  consists  in 
the  intermingling  of  South  and  North  American  forms  within 
the  limits  of  this  area,  rather  than  in  the  endemic  species,  and 
in  the  relationship  of  the  molluscan  fauna  to  that  of  the  West 
Indies.*  The  affinity  of  the  Antilles  with  South  America, 
however,  is  much  more  pronounced  than  with  North  America, 
if  we  exclude  Mexico.  The  distinctly  endemic  elements  of 
Central  America  and  the  West  Indian  islands  appear  to  have 
invaded  both  North  and  South  America  to  some  extent. 
The  family  Helicinidae  for  instance,  as  I  mentioned  (p.  157), 
is  probably  of  semi-tropical  origin,  its  range  indicating  that  it 
has  reached  America  from  the  west,  establishing  itself 
primarily  in  Central  America  and  the  West  Indies  at  a  very 
remote  time  of  geological  history.  The  operculate  land  mol- 
lusks, to  which  the  Helicinidae  belong,  are  of  great  faunistic 
interest.  Let  us  take  for  example  the  large  family  Cyclo- 
phoridae,  which  has  its  headquarters  in  southern  Asia  and 
southern  Europe.  In  America  the  family  is  almost  limited  to 
Central  and  South  America  and  the  West  Indian  islands. 
Only  in  Mexico  does  it  touch  North  American  territory.  As 
the  geographical  distribution  of  the  family  is  now  fairly  well 
known,  a  great  deal  of  interesting  information  can  be  derived 
from  its  study.  The  genus  Cyrtotoma  is  peculiar  to  southern 
Mexico.  Its  nearest  relations  are  Buckleyia  of  Colombia  and 
Ecuador,  and  Crocidopoma  of  Haiti,  Cuba  and  Jamaica.  The 

*  Martens,  L.  von,  "  Mollusks  of  Central  America,"  p.  xiv. 


EUROPEANS   IN   CENTRAL   AMERICA  257 

larger  genus  Amphicyclotus  has  its  centre  of  dispersal  in 
Colombia  and  Ecuador.  From  there  it  pressed  eastward 
through  Venezuela  into  Guiana  and  across  Trinidad  to  the 
island  of  Martinique,  which  must  have  been  connected  for 
some  time  with  the  southern  mainland.  In  Central  America 
the  genus  has  a  discontinuous  range.  A  few  species  occur 
in  Costa  Rica,  Guatemala  and  southern  Mexico.  Not  a  single 
species  is  known  from  the  Greater  Antilles. 

There  is  one  very  important  feature  in  the  fauna  of  Central 
America  which  I  have  scarcely  dwelt  on  as  yet,  and  that  is  its 
affinity  with  Europe.  It  is  not  at  all  striking.  Yet  it  does 
exist.  The  large  group  Diplommatininae  belonging  to  the 
family  Cyclophoridae  is  almost  entirely  confined  to  southern 
Asia,  the  Pacific  islands  and  Australia.*  Only  the  single 
genus  Adelopoma  occurs  in  America.  Its  wide  and  extremely 
discontinuous  range  in  the  New  World  marks  it  as  a  very 
ancient  immigrant,  for  it  is  likewise  known  from  Argentina, 
Peru,  Guatemala  and  Trinidad.  Now  the  Guatemalan  species 
(Adelopoma  stolli)  has  its  nearest  relation  in  the  Miocene 
beds  ,of  Oppeln  in  Silesia,  for  Professor  'Andreae  f  informs 
us  that  the  fossil  Adelopoma  martensi  occurring  in  these 
deposits  is  scarcely  distinguishable  from  a  species  inhabit- 
ing Central  America.  Our  first  impulse  on  hearing  of 
this  extraordinary  discovery  is  to  attribute  it  to  con- 
vergence or  even  misidentification.  But  the  identifica- 
tion has  been  confirmed  by  Professor  Boettger,  one  of  the 
most  eminent  of  European  specialists,  while  Adelopoma 
stolli  is  not  by  any  means  the  only  Central  American 
land  mollusk  that  possesses  European  affinities.  Many  other 
instances  will  be  alluded  to  in  the  next  chapter  (p.  265). 
Those  who  wish  to  interpret  all  cases  of  intimate  relationship 
between  American  and  European  forms,  as  arising  from  a 
remote  migration  across  a  hypothetical  Bering  Strait  land 
bridge,  will  find  it  difficult  to  reconcile  this  particular  occur- 
rence with  the  fact  that  no  Adelopomae  inhabit  any  part  of 
Asia  or  North  America. 

Professor  Stoll,J  who  made  a  special  study  of  the  mites  of 

*  Kobelt,  W.,  "Cyclophoridae." 

t  Andreae,  A.,  "  Binnenconchylienfauna  von  Oppeln,"  II.,  p.  23. 

t  Stoll,  0.,  "  Zoogeographie  d.  Wirbellosen,"  pp.  19—20. 

L.A.  S 


258  ORIGIN   OF   LIFE   IN   AMERICA 

Guatemala  during  a  residence  there  of  several  years,  states 
that  the  mite-fauna  of  Central  America  is  composed  of  the 
same  genera  as  that  of  middle  Europe.  In  some  cases  even 
the  species  are  identical.  It  is  true  that  most  of  these  genera 
also  inhabit  Asia,  though  Linopodes,  Haplophora,  Nicoletiella 
and  Uropoda  have  not  yet  been  recorded  from  that  continent. 
As  some  of  these  are  known  from  the  Oligocene  Baltic  amber 
deposits,  it  is  probable  that  the  genera  date  back  to  at  least 
early  Tertiary  times. 

Of  the  nearly  related  spiders  and  harvestmen,  Mr.  Pickard- 
Cambridge  *  remarks,  that  while  the  majority  of  the  Central 
American  species  are  peculiar  to  the  Nearctic  and  Neo- 
tropical regions,  the  genera  are  in  many  cases  identical  with 
those  of  the  Mediterranean  region,  India,  Australia  or  Africa. 
There  are  not  now  in  existence  any  land  connections,  he  con- 
cludes, which  an  arachnidal  fauna  could  take  advantage  of 
in  order  to  pass  from  Africa,  Australia  or  Europe  to  North 
or  South  America,  and  we  can  only  suggest  that  at  some 
period  or  other  these  now  widely  separated  regions  must 
have  been  linked  together  by  land  which  has  long  since  dis- 
appeared. 

The  various  groups  of  Central  American  insects  are  as  yet 
far  from  well  known,  and  their  relationships  with  the  insects 
of  other  regions  have  been  but  imperfectly  determined,  not- 
withstanding the  fact  that  Messrs.  Salvin  and  Godman  have 
published  a  series  of  fine  volumes  about  them.  The  consensus 
of  opinion  of  the  writers,  who  have  contributed  to  the 
"  Biologia  Centrali-Americana,"  is  that  Central  America 
is  .essentially  a  part  of  South  America.  The  purely  North 
American  forms  are  few  in  number,  their  southern  limit  being 
as  a  rule  in  Mexico.  This  verdict  agrees  also  with  that  of 
Dr.  Calvert,f  who  in  his  recent  researches  on  the  dragon - 
flies  (Odonata)  of  Mexico  and  Central  America,  comes  to  the 
conclusion  that  in  the  endemic  as  well  as  in  the  non-endemic 
species,  the  South  American  element  is  much  the  strongest. 

Before  concluding  this  chapter,  I  might  again  emphasize 
the  fact  that  the  occurrences  of  northern  genera  and  species 
in  Central  America  are  almost  all  discontinuous.  I  need  only 

*  Pickard- Cambridge,  O.,  "Araneidaof  Central  America." 

t  Calvert,  P.  P.,  "  Odonate  Fauna  of  Central  America,"  p.  467. 


DISCONTINUOUS  DISTRIBUTION  259 

mention  among  northern  plants,  the  oak  (Quercus)  and  the 
plane  (Platanus),  among  animals,  the  newt  Spelerpes,  the 
snapping  turtles  (Chelidridae)  and  the  fresh- water  mussels 
(Unionidae).  Many  other  northern  animals  and  plants  have 
a  similar  disjointed  range  in  the  midst  of  an  entirely  alien 
southern  fauna.  These,  and  the  northern  groups  that  are 
altogether  absent  from  Central  America,  but  reappear  much 
further  south,  are,  I  think,  part  of  a  very  ancient  invasion  of 
South  America.  If  it  is  true  that  the  South  American  animals 
and  plants  which  have  taken  almost  complete  possession  of 
Central  America,  poured  into  the  latter  from  the  south  in 
early  Pliocene  times,  surely  the  northern  groups  must  be 
immeasurably  older!  In  their  discontinuous  range  and  fre- 
quent isolation  on  mountain  tops  they  show  every  sign  of 
antiquity,  and  it  seems  likely  that  they  are  being  crowded 
out  rapidly  by  their  stronger  southern  rivals,  which  are  better 
fitted  to  support  the  present  climatic  conditions  of  this  region. 
Dr.  Wallace  *  suggested,  as  I  mentioned  above,  that  the 
northern  faunistic  affinity  of  South  America  which  is  so  cha- 
racteristic, especially  of  Chile,  but  which  we  find  to  some 
extent  all  along  the  Pacific  coast,  is  mainly  due  to  the  Glacial 
Epoch.  He  fancied  that  a  migration,  aided  by  gales  and  hurri- 
canes during  successive  Glacial  Epochs,  when  the  mountain 
range  of  the  Isthmus  of  Panama,  if  moderately  increased  in 
height,  might  have  become  adapted  for  the  passage  of  northern 
forms,  would  explain  all  these  extraordinary  features  of  distri- 
bution. Dr.  Wallace  thought  the  resemblance  only  consisted 
in  a  few  plants  and  insects.  He  had  very  little  idea  of  the  real 
extent  and  character  of  the  northern  element  that  has  actually 
penetrated  into  Central  and  South  America.  It  is  unlikely 
that  he  would  have  supported  these  views  had  he  known 
of  the  range  of  the  newts,  turtles,  freshwater  mussels  and 
other  groups.  Moreover,  we  also  have  evidence  of  ancient 
migrations  of  mammals  and  other  animals,  as  well  as  plants, 
in  an  inverse  direction  from  the  south  to  the  north.  It  is 
perfectly  certain,  therefore,  that  long  anterior  to  the  southern 
invasion  into  the  existing  area  of  Central  America,  two 
streams  of  animals  and  plants  passed  between  the  great 

*  Wallace,  A.  E.,  "  Distribution  of  Animals,"  II.,  p.  45. 

S2 


260  OKIGIN   OF   LIFE   IN   AMERICA 

continents,  leaving  certain  traces  of  their  transit  in  the 
more  ancient  portions  of  the  country.  And  yet  I  believe,  and 
shall  produce  ample  evidence  in  support  of  my  contention, 
that  only  certain  fragments  of  Central  America  formed  part 
of  that  land  which  long  ago  served  as  the  highway  between 
North  and  South  America.  This  fact  is  not  so  readily  re- 
vealed from  a  study  of  the  Central  American  animals  and 
plants.  All  we  can  gather  from  our  present  researches  is 
that  there  are  certain  ancient  elements  in  the  fauna  and  flora 
of  Central  America  exhibiting  affinities  with  North  America, 
Asia,  Europe,  Africa,  the  West  Indies  and  South  America,  and 
that  these  older  elements  are  being  dispossessed  or  driven  into 
the  more  inaccessible  parts  by  the  members  of  the  new  and 
most  recent  invasion  from  the  south  which  traversed  the  newly 
formed  Central  American  isthmus.  It  is  believed  that  this 
must  have  commenced  in  Pliocene  times.  Of  the  two  marine 
barriers  which  previously  prevented  this  southern  advance, 
one  was  in  the  neighbourhood  of  the  Panama  Canal,  the  other 
at  the  Isthmus  of  Tehuantepec,  but  to  judge  from  the  animals 
and  plants  of  Central  America,  the  former  had  already  dis- 
appeared when  the  more  northerly  one  was  still  in  existence. 


CHAPTEE  XI 

THE    WEST   INDIAN    ISLANDS 

NORTH  and  South  America  are  to  be  regarded,  according 
to  Professor  Suess,*  as  two  essentially  distinct  land-masses, 
between  which  is  interposed,  as  a  third  element,  the  area  of 
Central  America  and  the  Antilles.  This  geological  distinct- 
ness of  Central  America  and  the  Antilles  from  the  two  neigh- 
bouring continents  is  scarcely  recognisable  in  the  fauna  of  the 
great  isthmus.  But  the  West  Indies  are  comparable  to  a 
wedge  driven  in  between  two  faunistically,  more  or  less,  in- 
dependent and  distinct  land  masses.  Almost  everyone  who 
has  dealt  with  the  fauna  or  flora  of  the  West  Indian  islands 
has  expressed  his  surprise  at  this  fact.  In  position,  says  Dr. 
Walla ce,f  the  Antilles  form  an  unbroken  chain  uniting  North 
and  South  America,  in  a  line  parallel  to  the  great  Central 
American  isthmus.  Yet  instead  of  exhibiting  an  intermixture! 
of  the  productions  of  Florida  and  Venezuela,  they  differ 
widely  from  both  these  countries,  possessing  in  some  groups 
a  degree  of  speciality  only  to  be  found  elsewhere  in  islands  far 
removed  from  any  continent. 

One  other  important  feature  which  strikes  the  visitor  to 
the  islands  is  their  extreme  poverty  in  the  higher  groups  of 
animal  life.  It  is  not  that  the  Antilles  are  climatically  un- 
favourable to  animal  life.  On  the  contrary,  they  are  excep- 
tionally favoured  by  nature  to  support  a  luxuriant  and  varied 
fauna  and  flora.  Their  temperature  is  high  and  uniform, 
there  is  an  abundance  of  moisture,  the  soils  are  very  fertile, 
while  high  mountains  as  well  as  gentle  plains  abound,  at  least 
in  the  larger  islands.  Cuba,  the  largest  of  them,  exceeding 
Ireland  in  size,  and  being  far  more  favourably  situated,  has 

*  Suess,  E.,  "  Antlitz  der  Erde,"  I.,  p.  700. 

f  Wallace,  A.  E.,  "Distribution  of  Animals,"  II.,  p.  61. 


262  ORIGIN   OF   LIFE   IN   AMERICA 

not  half-a-dozen  species  of  land  mammals,  while  Ireland  pos- 
sesses nearly  three  times  that  number.  There  are  only  two 
ways  in  which  we  can  account  for  this  great  deficiency  in  the 
higher  animal  life  on  the  Antilles.  We  may  suppose  that 
either  the  islands  have  not  been  connected  with  the  mainland 
since  early  Tertiary  times,  or  if  they  have,  that  their  fauna 
was  largely  destroyed  since  their  isolation.  In  the  latter 
case  the  apparent  poverty  of  the  fauna  might  be  due  to  great 
destruction  of  animal  life  during  a  submergence  of  the  land, 
and  the  consequent  reduction  of  the  habitable  area.  On  the 
other  hand,  we  should  expect  the  relict  fauna  of  the  islands  to 
exhibit  marked  affinities  with  that  of  the  two  great  continents 
lying  to  the  north  and  south  respectively.  However,  as  I 
have  mentioned,  the  fauna  on  the  whole  is  essentially  dis- 
similar from  that  of  North  and  South  America.  The  problem 
of  the  origin  of  the  West  Indian  fauna,  therefore,  like  that  of 
Centra]  America,  is  much  more  complex  than  it  would  at  first 
sight  appear.  I  alluded  to  the  apparent  poverty  of  the  fauna 
because,  although  it  does  appear  very  poor  in  the  higher  groups 
some  of  the  lower  forms  of  animals  are  represented  by  a  large 
number  of  species.  The  land-snails,  in  fact,  are  extremely 
varied  in  character,  and  the  abundance  of  species  is  one  of  the 
most  remarkable  features  of  the  West  Indian  fauna.  A  study 
of  their  distribution  and  their  relationship  will  probably 
give  us  a  better  insight  into  the  origin  of  the  fauna  as  a  whole 
than  the  higher  vertebrates,  which  are  so  poorly  represented 
on  the  islands. 

Before  describing  the  molluscan  fauna  of  the  Antilles,  a 
few  preliminary  remarks  on  the  islands  may  not  be  out  of 
place.  The  islands  as  a  whole  form  a  natural  breakwater  or 
barrier  between  the  Atlantic  Ocean  on  the  one  hand,  and  the 
Gulf  of  Mexico  and  the  Caribbean  Sea  on  the  other,  which 
lie  on  the  opposite  side  of  it  (Fig.  13).  A  mere  glance  at  the 
map  is  sufficient  to  show  that  we  have  to  deal  with  two  distinct 
sets  of  islands.  A  series  of  large  ones  belong  together,  viz., 
Cuba,  Haiti  or  San  Domingo,  Jamaica  and  Portorico,  with 
mountain  crests  running  in  an  east-westward  direction,  while 
a  chain  o,f  the  much  smaller,  Anguilla,  Guadeloupe,  Dominica, 
Martinique,  St.  Vincent,  Barbados  and  others,  placed  in  north 
and  southward  position,  constitute  quite  an  independent 


GEOLOGY  OF   THE  WEST   INDIES  263 

group.  The  former  are  always  spoken  of  as  the  ''Greater 
Antilles,"  and  the  latter  as  the  "Lesser  Antilles."  With 
Professor  Suess  *  we  may  look  upon  the  mountain  ranges  of 
Yucatan  and  Guatemala,  which  trend  in  a  west-easterly  direc- 
tion, as  the  western  continuations  of  the  mountain  system  of 
the  Greater  Antilles.  The  latter,  as  well  as  a  few  of  the 
northern  Lesser  Antilles,  are  composed  of  sedimentary  rooks 
of  Mesozoic  and  Cainozoic,  possibly  even  of  Palaeozoic  age, 
while  many  of  the  remaining  smaller  islands,  which  cluster 
together  in  a  concave  arc,  seem  to  be  of  comparatively 
recent  volcanic  origin.  The  Bahamas,  and  some  of  the 
more  southerly  flat  islands,  including  part  of  Barbados,  are 
apparently  of  young  Tertiary  age.  The  whole  of  the  main 
series  of  the  Antilles,  from  Cuba  through  Jamaica,  Haiti  and 
Portorico  to  Barbados,  is  composed  of  similar  rocks.  Granite, 
older  eruptive  rocks,  serpentine,  glauconitic  sandstone  and 
cretaceous  limestone,  form  the  visible  remnants  of  a  once 
connected  mountain  range.  Westward  the  latter  divides  into 
several  branches.  One  of  them  passes  from  southern  Haiti 
through  Jamaica  to  Honduras,  another  by  way  of  Cuba  to 
Guatemala. 

There  is  some  evidence,  according  to  Professor  Hill,  that 
the  east  coast  of  North  America  lay  far  eastward  of  its  pre- 
sent site  in  pre- Cretaceous  times,  whereas  some  faunistic 
facts  point  to  a  continuation  of  this  condition  until  the 
Tertiary  Era.  The  Pacific  marine  fauna  transgressed  east- 
ward during  the  Jurassic  Period,  probably  across  the  Mexican 
plateau,  fossils  of  Pacific  type  having  been  found  in  western 
Cuba.  This  implies  that  the  barrier  separating  the  Atlantic 
from  the  Pacific  in, those  remote  times  must  have  been  situated 
to  the  east  of  Cuba.  Professor  Hill  f  argues  that  the  chain 
of  low-lying  islands  between  Florida  and  north-eastern  South 
America  represent  the  remnants  of  this  ancient  Jura-Cre- 
taceous isthmus  between  the  two  great  continents.  Whether 
such  a  land  bridge  existed  is  difficult  to  determine  from 
faunistic  evidence,  but  the  Atlantic  waters  seem  to  have 
entered  the  Caribbean  Sea  in  Lower  Cretaceous  times. 
During  part  of  the  Eocene  and  Oligocene  Periods,  extensive 

*  Suess,  E.,  "  Antlitz  der  Erde,"  I.,  pp.  700—707. 
t  Hill,  E.  T.,  "  Geology  of  Jamaica,"  pp.  200-216. 


264  ORIGIN  OF   LIFE   IN   AMERICA 

subsidences  drowned  the  Antilles  to  such  an  extent,  accord- 
ing to  Professor  Hill,  that  only  the  higher  summits  of  Cuba, 
Haiti  and  Jamaica  remained  above  sea-level  as  small  islands. 
The  West  Indian  islands  were  subsequently  raised  into  a  large 
continuous  and  connected  land.  In  late  Miocene  and  Pliocene 
times  the  gradual  and  final  dismemberment  of  the  Antillean 
lands  took  place.  Still  more  recently  a  further  elevation 
occurred,  not  sufficient,  however,  to  establish  a  united 
Antillean  continent.  Whether  Professor  Schuchert*  supports 
Professor  Hill's  hypothesis  of  a  wide  land  connection  be- 
tween Florida  and  Venezuela  in  late  Jurassic  times  is  not 
clearly  indicated  in  his  maps.  But  during  the  Cretaceous 
Period  all  the  West  Indian  islands  except  the  Bahamas  are 
represented  as  being  entirely  submerged.  In  Eocene  times 
the  greater  part  of  Cuba  was  above  sea-level.  In  the  succeed- 
ing Oligocene  Period  all  the  islands,  except  the  Bahamas, 
once  more  disappeared.  Thenceforth  all  the  Greater  Antilles 
retained  their  present  outlines.  Only  during  the  Plio- 
cene Period  was  there  a  land  connection  between  Cuba  and 
Yucatan.  All  these  writers  thus  concur  in  the  view  that  some 
time  during  the  earlier  part  of  the  Tertiary  Era  there  was  a 
very  profound  and  widespread  subsidence  of  almost  the  whole 
of  the  Antillean  area.  Yet,  according  to  Professor  Schuchert, 
the  Bahamas,  or  some  land  area  in  the  position  of  the 
Bahamas,  if  I  correctly  interpret  his  maps,  remained  above 
sea-level  practically  from  the  earliest  Palaeozoic  ages  to  the 
present  day.  The  idea  that  there  was  once  a  land  connection 
between  North  and  South  America  along  the  chain  of  the 
Lesser  Antilles,  Cuba,  the  Bahamas  and  Florida  is  also 
advocated  by  Professor  Gregory, f  though  he  admits  that 
the  area  of  the  Windward  islands  was  submerged  at  the  period 
when  the  oceanic  deposits  of  Barbados  were  laid  down.  There 
is  no  adequate  evidence,  he  thinks,  to  show  that  there  was 
more  land  at  any  subsequent  time  in  this  region  than  there 
is  at  present. 

Now  as  for  the  light  thrown  on  these  various  problems 
by  a  study  of  the  geographical  distribution  of  the  West  Indian 

*  Schuchert,  Charles,  "  Paleogeography  of  North  America,"  Maps  89— 
100. 
t  Gregory,  J.  W.,  "  Geology  of  the  West  Indies,"  p.  305. 


SNAILS   OF   THE   WEST   INDIES  265 

land  mollusks,  it  may  b©  urged,  in  the  first  instance,  that  the 
value  of  the  evidence  is  greatly  impaired  by  the  possibility 
of  occasional  or  accidental  dispersal.  That  a  certain  per- 
centage of  the  fauna  of  an  island  is  due  to  importation  by 
human  agency  is,  I  think,  well  established.  That  a  small 
proportion  of  the  West  Indian  fauna  may  possibly  have  been 
carried  from  island  to  island  and  from  the  mainland  by  other 
accidental  means  is  likewise  possible.  But  I  quite  concur 
with  Dr.  Simpson  in  his  belief  that  we  are  not  justified  in 
explaining  the  whole  distribution  of  the  terrestrial  mollusks  in 
the  West  Indian  islands  by  such  an  hypothesis.  The  very 
nature  of  the  West  Indian  fauna,  and  its  distinctness  from 
that  of  the  neighbouring  continents,  precludes  the  assumption 
of  any  extensive  accidental  dispersal.  Hence  we  may  take  for 
granted  the  correctness  of  the  theory  that  the  main  mass  of 
these  mollusks  have  migrated  from  island  to  island  when  the 
latter  formed  a  united  land  surface.  This  belief  is  vouched 
for,  moreover,  by  the  fact  that  the  study  of  practically  all 
other  groups  of  West  Indian  animals  brings  us  to  precisely 
the  same  conclusion.  In  their  general  agreement  with  the 
results  arrived  at  from  a  geological  study,  all  these  groups 
tend  to  show  that  the  study  of  geographical  distribution  is  a 
science  of  profound  importance  as  an  indicator  of  former 
changes  of  land  and  water. 

The  facts  adduced  by  Dr.  Simpson,  that  the  operculate 
species  form  so  large  a  proportion  of  the  Antillean  land- 
snail  fauna,  that  a  majority  of  the  genera  is  found  on  two 
or  more  of  the  islands  and  the  mainland,  while  nearly  every 
species  is  absolutely  restricted  to  a  single  island,  is  a  strong 
testimony  in  favour  of  a  former  general  land  connection  in 
this  area.  Dr.  Simpson  *  very  carefully  compared  the  mol- 
luscan  fauna  of  the  various  islands  with  one  another  and  with 
that  of  the  mainland,  and  bases  his  conception  of  the  geolo- 
gical history  of  the  Antilles  mainly  on  the  results  so  derived. 
He  believes  a  considerable  portion  of  the  species  inhabiting 
the  Greater  Antilles  to  be  ancient,  and  to  have  developed  on 
the  islands  where  they  are  now  found.  Probably  some  time 

*  Simpson,  C.  T.,  "  Distribution  of  Mollusks  in  West  Indies,"  pp.  447— 

448. 


266  ORIGIN   OF   LIFE   IN   AMERICA 

during  the  Eocene  Period  the  Greater  Antilles  were  at  a 
higher  level,  so  that  the  islands  were  united  with  one  another 
and  with  Central  America.  This  resulted  in  an  exchange  of 
species  between  the  two  regions.  A  land  connection  is  also 
indicated  between  Cuba,  the  Bahamas  and  Florida.  At  this 
time,  he  thinks,  the  more  northern  isles  of  the  Lesser  Antilles 
were  not  yet  elevated  above  the  sea,  or,  if  so,  they  have  since 
probably  been  submerged.  After  this  period  of  elevation 
there  followed  one  of  general  subsidence.  During  it  Jamaica 
was  the  first  island  to  be  separated,  then  followed  Cuba,  and 
afterwards  Haiti  and  Portorico.  The  connection  between 
the  Antilles  and  the  mainland  was  broken,  while  the  subsi- 
dence continued  until  only  the  summits  of  the  mountains  of 
the  four  Greater  Antillean  Islands  remained  above  water. 
Eventually  there  was  another  period  of  elevation  which  lasted, 
no  doubt,  until  the  present  time.  The  Bahamas  gradually 
emerged  and  were  populated  by  forms  drifted  from  Cuba  and 
Haiti.  In  this  last  conclusion  Dr.  Simpson  unfortunately 
fails  to  appreciate  the  full  value  of  his  own  studies.  If  all 
the  snails,  amphibians  and  reptiles  known  to  inhabit  the 
Bahamas — and  many  of  them  are  peculiar  to  these  islands — 
had  reached  them  by  accidental  dispersal,  this  mode  of  con- 
veyance must  be  of  enormous  importance.  In  such  a  case 
I  think  we  should  scarcely  be  justified  in  basing  our  theories 
of  the  geological  history  of  the  Antilles  on  the  geographical 
distribution  of  animals. 

Now  among  the  families  of  snails  alluded  to  in  Dr.  Simp- 
son's paper  as  being  abundant  in  the  West  Indies,  there  are 
some  that  have  received  special  attention  by  American 
malacologists.  One  of  these,  the  Urocoptidae,  or  Cylindrel- 
lidae  as  they  were  formerly  called,  comprises  small  snails 
with  an  elegant  fusiform  shell  composed  of  many  narrow 
whorls.  They  are  found  in  the  Antilles,  in  southern  Florida, 
along  the  northern  coasts  of  South  America,  in  Central 
America  and  in  Mexico,  as  well  as  the  adjacent  parts  of  the 
United  States.  The  centre  of  distribution  thus  lies  in  the 
West  Indies. 

Since  it  has  been  proved  by  fossil  evidence  in  Jamaica  that 
numerous  sub-generic  groups  of  land  snails,  in  essentially 
their  modern  forms,  were  established  before  the  close  of  the 


ANTIQUITY   OF   SNAILS  267 

Oligocene  Period,  generic  differentiation  probably  dates  from 
a  much  earlier  time.  Indeed,  Dr.  Pilsbry  *  is  of  opinion  that 
the  first  radiation  of  the  Antillean  group  of  the  Urocoptidae 
may  have  occurred  on  a  Mesozoic  Antillean  land  area.  The 
succeeding  Eocene  depression,  he  thinks,  isolated  various 
branches  of  the  existing  stocks,  western  Cuba  being  pro- 
bably the  first  fragment  to  be  dismembered.  It  was  probably 
not  until  near  the  close  of  the  Tertiary  that  continuity  of 
land  was  restored  with  east  Cuba.  Haiti  and  Jamaica  would 
seem  to  have  remained  united  after  both  western  and  eastern 
Cuba  had  seceded.  Finally,  these  islands  were  widely 
separated  by  the  subsidence  culminating  at  the  end  of  the 
Eocene,  or  in  the  beginning  of  the  Oligocene  Period.  This 
depression  was  again  followed  by  an  elevation  in  later  Oligo- 
cene times,  and  it  is  likely  that  there  was  a  transitory  connec- 
tion between  Jamaica  and  Haiti.  Between  the  latter  and 
Cuba  the  land  connection  probably  lasted  longer,  thus  pro- 
ducing the  homogeneous  distribution  of  several  groups.  It 
is  likely,  says  Dr.  Pilsbry,  that  during  this  mid-Oligocene 
elevation,  the  Haitian  land  included  Portorico,  the  Virgin 
islands  and  the  islands  of  the  Anguilla  bank,  that  is  to  say, 
some  of  the  northern  group  of  the  Lesser  Antilles.  Dr. 
Pilsbry  argues  that  the  presence  of  large  fossil  mammals  of 
South  American  type  (Amblyrhiza  and  Loxomylus)  in  Plio- 
cene deposits  of  Anguilla  demonstrates  that  the  whole  Carib- 
bean chain  of  islands  was  elevated  into  a  ridge  connected 
with  South  America  during  the  Pliocene  Period.  He  likewise 
expresses  the  opinion  that  the  genus  Brachypodella,  one  of 
the  Urocoptidae,  extended  its  range  westward  to  Yucatan. 
Nevertheless,  he  contends  that  there  is  but  scanty  evidence  of 
any  direct  land  connection  between  the  Greater  Antilles  and 
the  mainland  of  Central  America  during  the  whole  of  Tertiary 
time. 

Thus,  while  differing  from  Dr.  Simpson  on  several  minor 
points,  Dr.  Pilsbry's  careful  researches  confirm  his  view, 
and  that  of  many  geologists,  that  originally  there  was  a  large 
area  of  land  of  which  the  Antilles  are  the  last  remnants,  and 
that  some  time  during  the  Tertiary  Era  almost  the  whole  of 

*  Pilsbry,  H.,  "Manual  of  Conchology,"  XVI.,  pp.  xx.— xxiv. 


268  ORIGIN   OF   LIFE   IN   AMERICA 

this  old  land  was  submerged  having  since  gradually  regained 
its  present  position. 

The  great  age  of  the  West  Indian  fauna  and  the  inter -re- 
lationship between  the  islands  and  the  mainland  is  well  exem- 
plified by  the  ancient  family  of  operculate  snails — the 
Cyclophoridae.*  The  genus  Neocyclotus  inhabits  principally 
northern  South  America  and  the  Antilles.  From  this 
apparently  very  old  centre  of  dispersal  some  members  of 
the  genus  have  pushed  southward  as  far  as  Peru  in  the  west 
and  Rio  de  Janeiro  in  the  east.  A  few  have  entered  Central 
America.  One  distinct  group  (Plectocyclotus)  has  no  less 
than  thirty-two  species  in  Jamaica  and  only  one  in  Portorico. 
Another  genus  (Crocidopoma)  is  entirely  confined  to  Jamaica, 
Haiti  and  eastern  Cuba.  This  indicates  strikingly  the  re- 
lationship of  the  three  Great  Antilles  and  their  distinctness 
'from  western  Cuba,  which  was  already  pointed  out  by  Dr. 
Pilsbry,  while  geologists  maintain  that  western  Cuba  was 
submerged  quite  independently  from  the  remainder  of  the 
islands.  It  also  illustrates  the  extreme  slowness  with  which 
the  dispersal  of  these  mollusks  takes  place. 

Still  more  instructive  is  the  whole  group  to  which 
Crocidopoma  belongs.  With  Cyrtotoma,  Amphicyclotus  and 
Buckleya,  it  forms,  as  already  mentioned  (p.  256),  a  group 
of  closely  related  genera  of  operculate  snails.  I  alluded 
also  to  the  fact  that  three  of  them  had  a  discontinuous  range 
in  Central  America,  and  that  Amphicyclotus  had  apparently 
travelled  eastward  from  Ecuador,  invading  Venezuela  and 
Guiana,  and  had  thence  passed  into  the  islands  of  Martinique, 
Guadeloupe  and  Dominica,  when  the  latter  were  connected 
with  one  another,  and  with  the  mainland.  It  might  be 
urged  that  accidental  dispersal  is  responsible  for  their 
presence  on  these  islands.  'But  we  have  no  reason  for  such  a 
supposition,  because  the  species  occurring  on  the  islands  are 
quite  distinct  from  one  another  and  from  those  of  Venezuela. 
Some  evidence  is  afforded  by  these  snails  for  the  belief  that 
the  Lesser  Antilles  are  remnants  of  older  land  which  ex- 
tended northward  from  Venezuela,  although  all  the  visible 
parts  of  the  islands  are  covered  by  modern  volcanic  deposits. 

*  Kobelt,  W.,  "  Cyclophoridae." 


DISPEBSAL   OF   SNAILS  269 

We  are  top  apt  to  argue  that  the  fauna  of  an  island  covered 
by  recent  volcanic  deposits  must  necessarily  have  been  derived 
by  occasional  means  of  dispersal.  I  need  only  cite  the  case  of 
the  Galapagos  islands,  which  are  entirely  volcanic,  and  have 
seemingly  risen  from  the  floor  of  the  ocean.  Nevertheless, 
it  can  be  demonstrated  from  a  faunistic  point  of  view,  as  I 
shall  show  later  on,  that  they  have  once  formed  part  of  an 
ancient  continuous  land  surface. 

Still  another  group  of  operculate  land  snails  contains  the 
two  genera  Megalomastoma  and  Tomocyclus.  The  centre 
of  dispersal  is  Cuba,  chiefly  the  western  part  of  the  island. 
From  there  Megalomastoma  reached  Haiti,  Portorico  and  the 
Virgin  islands,  which  lie  close  to  the  latter.  Tomocyclus 
inhabits  only  southern  Mexico  and  Guatemala.  Thus  it 
seems  probable  that  Cuba,  Guatemala,  and  southern  Mexico 
were  connected  with  one  another  by  land  in  very  remote 
times. 

Let  us  take  as  another  example,  that  of  the  ancient  and 
large  family  Bulimulidae.  In  another  chapter  I  have  dwelt 
on  the  great  age  of  this  family  of  snails  _(p.  209)  and  its 
general  range.  It  contains  mostly  large,  ponderous  snails 
with  somewhat  conical  shells.  Anatomically  they  are  re- 
lated to  the  Helicidae.  Although  represented  by  a  great 
many  species,  only  a  few  genera  enter  the  West  Indies.  One 
of  these  (Plekocheilus)  inhabits  almost  exclusively  Guiana, 
Venezuela,  Colombia,  Ecuador,  Peru  and  Bolivia,  that  is  to 
say  the  northern  and  western  States  of  South  America,  where 
the  different  species  are  often  found  at  great  heights  in  the 
mountains.  Only  two  species  enter  the  West  Indies,  viz., 
P.  aurissileni,  which  is  peculiar  to  St.  Vincent,  and  P.  aula- 
costylus,  which  is  only  met  with  in  the  island  of  St.  Lucia. 
These  islands  are  two  of  the  most  southern  group  of  the 
Lesser  Antilles.  The  ancestors  of  the  two  species  of  Pleko- 
cheilus have  probably  entered  these  islands  when  the  latter 
were  connected  with  one  another  and  with  the  mainland  of 
Venezuela,  and,  as  the  species  are  very  distinct  from  one 
another,  this  could  not  have  happened  within  very  recent 
geological  times. 

The  species  of  the  genus  Bulimulus,  as  I  have  already  had 
occasion  to  state,  are  exceedingly  difficult  to  discriminate 


270  ORIGIN   OF   LIFE   IN   AMERICA 

from  one  another.  Dr.  Pilsbry  divided  them  roughly  into 
three  groups,  only  one  of  which  inhabits  the  Antilles.  To 
trace  the  relationship  of  the  various  species  to  one  another 
seems  to  he  a  task  even  beyond  the  powers  of  this  distin- 
guished American  conchologist.  The  minor  sections  being 
arranged  geographically  in  Dr.  Pilsbry's  work,  it  does  not 
enable  us  to  draw  any  conclusions  as  to  their  former  dis- 
persals. One  interesting  fact,  however,  has  been  brought  to 
light,  which  proves  not  only  the  antiquity  of  this  family  but 
the  .extraordinary  persistency  of  specific  characters  among 
some  of  its  members.  The  Oligocene  Bulimulus  americanus 
of  Florida  is  practically  identical  with  B.  ridleyi,  still  living 
on  the  island  of  Fernando  de  Noronha. 

The  genus  Drymaeus  (OtostomusJ,  which  is  as  difficult  to 
classify  as  Bulimulus,  has  mainly  a  continental  range. 
Only  a  few  species  live  in  the  West  Indies.  Among  these 
we  likewise  notice  a  remarkable  persistency  of  specific 
characters.  Drymaeus  dormani,  for  instance,  occurs  in 
southern  Florida,  while  the  closely  allied  D.  dominicus  is 
resident  in  Haiti,  Cuba,  Florida,  Yucatan,  Nicaragua  and 
Mexico.  At  the  first  thought  we  might  feel  inclined  to  attri- 
bute such  a  strikingly  discontinuous  range  to  accidental  dis- 
tribution ;  but  a  careful  study  of  the  whole  family  has  im- 
pressed me  with  the  conviction  that  we  have  to  deal  with  a 
set  of  very  ancient  and  very  persistent  types  of  mollusks. 

Even  less  satisfactory  to  identify  than  Bulimulus  and 
Drymaeus  are  the  Orthalicinae,  another  large  group  of  Buli- 
mulidae.  Dr.  Strebel  *  has  recently  undertaken  their  revision, 
utilising  several  characters  which  had  hitherto  not  been  em- 
ployed in  the  discrimination  of  the  species.  It  is  an  attempt, 
at  least,  to  trace  the  complex  relationship  of  the  innumerable 
closely  allied  forms,  although  the  author  does  not  seem  to 
realize  the  great  antiquity  of  the  group.  His  arguments  in 
favour  of  wholesale  accidental  dispersal,  even  from  western 
Mexico  to  the  Antilles,  are  quite  at  variance  with  the  lesson 
the  study  of  the  West  Indian  fauna  has  taught  us.  The  species 
of  Simpulopsis  are  mostly  South  American,  but  a  small  aber- 
rant group  with  smooth  apical  whorls  is  confined  to  Portorico, 

*  Strebel,  H.,  "  Eevision  der  Orthalicinen." 


MOLLUSCAN   AFFINITIES  .271 

Haiti  and  Mexico.  The  genus  Gaeotis  is  quite  confined  to 
Portorico,  while  Amphibulima  is  limited  to  the  Lesser 
Antilles.* 

All  these  studies  yield  the  same  fundamental  results, 
namely,  the  presence  within  the  Antillean  area  of  an  ex- 
tremely ancient  stock  distantly  related  to  that  of  Central 
America  and  northern  South  America.  After  this  fauna 
had  developed  to  some  extent,  a  widespread  destruction 
apparently  took  place,  due  probably  to  submergence,  fol- 
lowed by  a  reimmigration  from  the  south  and  west.  A 
more  precise  knowledge,  however,  of  the  minor  physical 
changes  which  the  West  Indian  islands  have  undergone 
can  be  acquired  when  we  compare  the  results  derived 
from  the  sedentary  or  slowly  moving  mollusks  with  those 
drawn  from  the  more  active  members  of  the  fauna.  But 
there  is  one  more  element  of  importance  in  the  Antillean 
molluscan  fauna  which  has  not  yet  been  considered.  It 
is  especially  in  view  of  the  remarks  I  made  in  the  ninth 
chapter,  on  the  striking  relationship  of  the  south-western 
American  fauna  to  that  of  Europe,  that  I  wish  to  direct  par- 
ticular attention  to  the  European  affinities  of  the  Antillean 
fauna. 

I  think  it  was  Dr.  Kobelt  f  who  first  animadverted  on  the 
resemblance  between  the  European  molluscan  fauna  and  that 
of  ,the  Antilles  and  Central  America.  At  first  sight,  as  he 
remarks,  the  two  faunas  seem  to  be  as  distinct  as  any  disciple 
of  the  principle  of  multiple  centres  of  creation  could  wish. 
After  a  careful  study,  however,  we  certainly  perceive  distinct 
traces  of  relationship.  The  carnivorous  snail  Glandina,  which 
is  represented  in  the  Mediterranean  region  of  Europe  by  a 
single  species,  has  its  headquarters  in  the  Antilles  and  in 
the  surrounding  States.  It  cannot  be  looked  upon  as  a  recent 
introduction  to  Europe,  because  its  discontinuous  range  be- 
between  the  Caucasus  and  Algeria  is  altogether  opposed  to  any 
such  supposition.  Several  species  of  Glandina,  moreover, 
occur  in  French  and  English  Eocene,  Oligocene  and  Miocene 
deposits,  some  of  them  being  almost  identical  with  still 

*  Pilsbry,  H.  A.,  "Manual  of  Conchology,"  Yols.  X.— XII. 
f  Kobelt,  W., "  Verhaltniss  d.  Europaischen  Landmolluskenfauna,  &c.," 
p.  145—148. 


272  ORIGIN   OF   LIFE   IN  AMERICA 

existing  American  forms.  The  operculate  genera  Tudorella 
and  Leonia  of  the  Mediterranean  region  are  certainly  related 
to  West  Indian  forms,  though  not  so  closely  as  was  formerly, 
believed.  These  and  other  considerations  induced  Dr.  Kobelt 
to  postulate  a  land  connection  between  Europe  and  North 
America,  which  was  only  severed  in  Miocene  times.  The 
German  Miocene  genus  Subulina,  the  large  Glandinae  and  the 
early  Tertiary  European  Oleacinae,  are  considered  by  Pro- 
fessor Boettger  *  as  the  nearest  relations  or  direct  ancestors 
of  Central  America  or  West  Indian  genera  and  species.  The 
same  authority  also  alludes  to  the  American  facies  of  the 
Tertiary  flora  of  Europe,  and  concludes  that  a  land  bridge 
right  across  the  Atlantic  Ocean  existed  up  to  early  Miocene 
times.  Finally  Professor  Andreaef  supports  the  same  theory, 
on  account  of  the  occurrence  of  the  West  Indian  Boltenia, 
Strobilus  and  Pleurodonte  in  the  Miocene  deposits  of  Silesia 
in  Germany.  And  he  was  the  first  to  definitely  fix  the  posi- 
tion of  the  land  connection  as  one  uniting  western  Europe 
with  the  Antillean  area. 

Still  other  features  of  relationship  between  these  regions 
remain  to  be  considered.  Long  ago  Mr.  Woodward  J  pointed 
out  that  the  presence  of  the  European  genus  Clausilia  in  the 
West  Indies  and  in  northern  South  America  (see  Fig.  19) 
implied  the  existence  of  a  former  more  direct  land  way  across 
the  Atlantic  than  would  be  afforded  by  the  land  connection 
which  was  supposed  to  have  once  united  the  boreal  regions 
of  Europe  and  North  America.  Since  that  time  others  have 
repeated  his  assertion.  Clausilia  is  now  known  to  have  lived 
in  Europe  since  Cretaceous  times,  and  has  probably  originated 
there.  It  is  partial  to  high  altitudes,  large  numbers  of  species 
being  found  in  the  Alps,  the  Dalmatian  mountains  and  the 
Caucasus.  Only  a  single  European  species  resembles  the 
American  group  (Nenia),  namely  Clausilia  pauli  of  the 
western  Pyrenees,  and  it  is  so  closely  related  to  the  members 
of  that  group  that  both  Mr.  Bourguignat  and  Mr.  Locard, 
two  French  conchologists  of  the  "  nouvelle  ecole,"  failed  to 
find  any  satisfactory  difference  between  them.  It  is  quite 

*  Boettger,  0.,  "  Verwandschaftsbeziehungen  d.  Helix  Arten,"  p.  116. 
t  Andreae,  A.,  "  Binnenconchylienfauna  d.  Miocans,"  II.,  p.  31. 
\  Woodward,  S.  P.,  "  Manual  of  the  Mollusca,"  p.  112. 


MOLLUSCAN   AFFINITIES  273 

true  that  another  group  of  Clausilia,  known  as  Garnieria,  from 
tropical  and  eastern  Asia  also  approaches  the  American  group 
closely.  Yet  the  fact  that  no  Clausilia,  either  fossil  or  recent, 
has  ever  been  discovered  in  northern  Asia  or  North  America, 
although  many  species,  as  I  remarked,  thrive  in  high  altitudes 
and  cold  climates,  speaks  strongly  against  the  supposition  of 
the  ancestors  of  the  West  Indian  and  South  American  stock 
having  wandered  through  Asia  and  North  America  to  these 
regions.  The  geographical  distribution  of  Clausilia  thus 
offers  one  of  the  most  cogent  arguments  in  favour  of  a  direct 
land  bridge  between  the  Mediterranean  and  the  Antillean 
regions.  Opponents  of  this  view  may  urge  that  Clausilia  is 
merely  represented  by  a  single  species  in  the  West  Indies, 
while  none  are  known  from  Central  America.  We.  may  explain 
this  curious  circumstance  by  the  fact  that  the  West  Indies 
were  submerged  probably  before  the  newly  immigrated  Clau- 
silias  had  time  to  gain  possession  of  the  higher  eminences, 
so  that  most  of  them  would  have  been  destroyed.  In  Central 
America  fewer  traces  of  European  affinity  have  been  detected 
than  in  western  North  America  or  western  South  America, 
because  in  the  latter1  regions  the  faunas  remained  more  or  less 
isolated  for  long  periods,  while  the  great  rush  of  South 
American  invaders,  combined  with  climatic  changes,  swept 
all  before  them  in  Central  America.  Why  Clausilia  has  suc- 
ceeded in  reaching  western  South  America  without  attaining 
western  North  America  will  be  discussed  in  the  neixt  chapter 
but  one. 

Dr.  Simroth  suggests  that  the  ancestors  of  the  American 
Bulimulidae,  at  least  the  group  of  Orthalicinae,  may  be  of 
European  origin,  while  I  venture  to  think  that  the  curious 
Bumina  decollata,  which  is  supposed  to  be  a  human  importa- 
tion in  Cuba,  may  be  indigenous  there,  since  it  is  now  known 
to  have  lived  unchanged  in  the  Mediterranean  region  since 
Oligocene  times.  In  view  of  my  remarks  in  previous  chapters 
on  the  relationship  of  the  North  American  snake  Tropido- 
notus,  of  the  crayfish  Potamobius,  of  the  slugs  belonging 
to  the  family  Arionidae,  of  the  glass  snake,  of  all  that  remark- 
ably European  assemblage  of  animals  in  the  south  western 
States,  of  the  snail  Adelopoma  in  Guatemala  and  numerous 
other  instances,  such;  as  the  range  of  the  flamingoes,  it  need 

L.A.  T 


274  ORIGIN   OF   LIFE   IN   AMERICA 

not  'be  surprising  that  I  am  a  strong  adherent  of  the  theory 
just  stated,  that  a  land  bridge  existed  right  across  the  Atlantic 
between  the  Mediterranean  and  the  Antillean  regions,  and 
that  the  European  element  of  the  fauna  made  use  of  it  in 
passing  to  America  (Fig.  14).  This  land  connection,  of 
course,  was  quite  independent  of  the  one  I  described  (p.  13) 
as  having  once  joined  Labrador  and  Scotland  by  way  of 
Greenland.  The  latter  may  possibly  have  come  into  existence 
when  the  other  had  already  crumbled  away.  At  any  rate,  the 
two  are  quite  distinct  as  to  age  and  position. 

Before  I  had  an  opportunity  of  making  this  more  thorough 
study  of  the  North  American  fauna,  I  was  under  the  impres- 
sion that  the  "  Southern  Atlantis,"  as  we  may  call  this  land 
connection,  joined  Africa  with  South  America,  and  that  there 
was  no  other  land  bridge  across  the  mid- Atlantic.*  I  am  still 
an  advocate,  as  I  shall  explain  more  fully  later  on,  of  what 
Dr.  von  Ihering  calls  "  Archhelenis,"  the  hypothetical  con- 
tinent of  the  southern  part  of  the  Atlantic  Ocean.  But  I 
maintain  that  a  more  northerly  land  bridge  likewise  existed, 
and  that  the  two  were  completely  separated  by  a  wide  ocean. 

The  disciples  of  Dr.  Wallace  will  exclaim,  "  What  about  the 
permanence  of  ocean  basins,  a  theory  which  receives  such 
weighty  support  from  some  of  the  most  eminent  geologists 
of  the  day  ?  "  This  question  of  the  permanence  of  ocean 
basins,  and  we  may  say  of  continental  areas  too,  really  lies  at 
the  root  of  most  of  our  inquiries  into  the  past  changes  of  the 
earth  and  its  animal  inhabitants.  The  internal  characters 
of  the  rocks  we  see  around  us,  remarks  Sir  Archibald  Geikie,f 
point  unmistakably  to  deposition  in  comparatively  shallow 
water.  "Their  abundant . intercalations  of  fine  and  coarse 
material,  their  constant  variety  of  mineral  composition,  their 
sun-cracks,  ripple-marks,  rain-pittings  and  worm-tracks, 
their  numerous  unconformabilities  and  traces  of  terrestrial 
surfaces,  together  with  the  prevalent  facies  of  their  organic 
contents,  combine  to  demonstrate  that  the  main  mass  of  the 
sedimentary  rocks  of  the  earth's  crust  was  accumulated  close 
to  land,  and  that  no  trace  of  really  abysmal  deposits  is  to  be 
found  among  them."  From  these  considerations,  says  Sir 

*  Scharff,  E.  F.,  "  Atlantis  Problem,"  p.  279. 
t  Geikie,  A.,  "Text  Book  of  Geology,"  p.  911. 


THE   ANCIENT   ATLANTIS  275 

Archibald  Geikie,  we  are  led  to  the  conclusion  that  the  pre- 
sent continental  areas  must  have  been  terrestrial  regions 
of  the  earth's  surface  from  a  remote  geological  period. 
Subject  to  repeated  oscillations,  continues  Sir  Archibald 
Geikie,  so  that  one  tract  after  another  has  disappeared 
and  reappeared  from  beneath  the  sea,  the  continents s 
though  constantly  varying  in  shape  and  size,  have  yeit 
maintained  their  individuality.  So  far,  I  think,  most 
geologists  will  agree  with  Sir  Archibald  Geikie.  It  is  his 
inference,  that  the  existing  ocean  basins  have  probably  always 
been  the  great  depressions  of  the  earth's  surface,  which  has 
not  met  with  such  general  approval.  Dr.  Wallace  supports 
Sir  Archibald  Geikie's  view  on  the  grounds,  not  only  of  the 
enormous  depths  and  great  extent  of  the  oceans,  and  of  the 
circumstance  that  the  deposits  now  forming  in  them  are 
distinct  from  anything  found  upon  the  land  surface,  but  also 
owing  to  the  supposed  extraordinary  fact  that  the  countless 
islands  scattered  over  their  whole  area  (with  one  or  two  ex- 
ceptions) never  contain  any  Palaeozoic  or  Secondary  rocks, 
that  is,  have  not  preserved  any  fragments  of  ancient  con- 
tinents, nor  of  the  deposits  which  must  have  resulted  from 
their  denudation  during  the  whole  period  of  their  existence ! 
The  exceptions  alluded  to  by  Dr.  Wallace*  are  New  Zealand 
and  the  Seychelles  islands,  both  situated  near  to  continents 
and,  according  to  the  same  writer,  not  really  oceanic.  "The 
vast  areas  of  the  Atlantic,  Pacific,  Indian  and  Southern 
Oceans  are  thus  left  almost  without  a  solitary  relict  of  the 
great  islands  or  continents  which  some  naturalists  believe  to 
have  sunk  beneath  the  waves  of  these  oceans."  Thus  writes 
Dr.  Wallace.  Another  argument  in  favour  of  the  permanence 
of  ocean  basins  has  recently  been  brought  forward  by  Pro- 
fessor Joly.f  It  is  based  on  the  facts  of  solvent  denudation. 
He  regards  the  sodium  in  the  O'Cean  as  the  key  to  the  history 
of  solvent  denudation,  arguing  that  it  was  derived  from  the 
igneous  rocks  of  the  earth  by  the  processes  of  weathering  and 
solution  progressing  throughout  geological  time.  He  shows 
that  the  quantity  of  oceanic  sodium  agrees  with  the  sediments 

*  Wallace,  A.  E.,  "  Island  Life,"  p.  105. 
t  Joly,  J.,  "Radioactivity  and  Geology,"  pp.  127—131. 

T2 


276  ORIGIN   OF   LIFE   IN  AMERICA 

as  we  find  them  upon  the  existing*  continents,  and  concludes 
that  there  cannot  be  yet  other  continents  with  their  own 
burdens  of  sediment  hidden  beneath  the  ocean.  That  former 
continents  of  any  antiquity  or  magnitude  are  not  hidden 
beneath  the  waves,  says  Professor  Joly,  seems  certain, 
unless  the  estimates  of  sediments  are  quite  erroneous. 
Whether  the  estimates  are  correct  is  a  question  which  must 
be  left  to  authorities  in  physical  chemistry ;  but  it  has  been 
argued  by  Professor  Carthaus  *  that  the  waters  of  the 
ocean,  as  well  as  those  of  continents,  were  originally  rich  in 
sodium  chloride,  and  that  fresh-water  organisms  only  came 
into  existence  comparatively  recently,  that  is  to  say  in  late 
Mesozoic  times.  When  we  consider  the  enormous  area  of 
North  America  that  was  under  water  in  Cretaceous  times  for 
instance,  less  than  an  equivalent  strip  of  land  in  the  shape  of  a 
trans -Atlantic  land  bridge  would  be  all  that  is  required  for  our 
purpose.  We  need  not  call  it  a  continent. 

As  for  the  arguments  in  favour  of  the  permanence  of  con- 
tinents and  ocean  basins  raised  by  Sir  Archibald  Geikie  and 
Dr.  Wallace,  they  are  based  on  the  following  facts  and 
assumptions,  viz.,  great  ocean  depths,  absence  of  abysmal 
rocks  on  present  land  surfaces,  and  absence  of  older  Mesozoic 
or  Palaeozoic  rocks  (with  one  or  two  exceptions)  on  oceanic 
islands.  It  has  been  shown,  however,  by  Professor  Suess  that 
great  depressions  on  the  surface  of  the  earth's  crust  are  not 
necessarily  old  or  permanent.  Quite  near  the  south-west 
coast  of  Asia  Minor,  and  close  to  the  mighty  Ak  Dagh  (10,000 
feet  high),  a  depth  of  over  10,000  feet  has  been  recorded.  This 
depth  is  all  the  more  remarkable  when  we  consider  that  fresh- 
water Pliocene  beds  of  the  mainland  are  continued  across  to 
the  neighbouring  island  of  Ehodes,  thus  showing  that  the 
latter  was,  until  such  a  recent  geological  period  as  the  Plio- 
cene, still  joined  to  the  continent.  Altogether  Professor 
Suessf  inclines  to  the  view  that  geological  evidence  does  not 
prove,  nor  even  point  to  a  permanence  of  the  great  depths, 
at  least  in  the  oceans  of  the  Atlantic  type.  The  next  point 
which  has  been  raised  in  favour  of  the  view  of  the  permanence 

*  Carthaus,  E.,  "  Klimatische  Verhaltnisse  der  Geologischen  Vorzeit." 
t  Suess,  E.,  "  Are  Great  Ocean  Depths  Permanent  ?  "  pp.  182—186. 


PERMANENCE   OF   OCEAN   BASINS  277 

of  oceans  and  continents  is  the  supposed  absence  of  abysmal 
deposits  on  any  existing  land  surface.  The  discovery,  how- 
ever, of  true  deep-sea  ooze  in  Barbados  and  Cuba  shows  that 
this  argument  is  no  longer  valid.*  There  only  remains  one 
other  argument  in  favour  of  this  theory,  and  that  is  the 
structure  of  the  oceanic  islands.  With  two  exceptions,  re- 
marks Pr.  Wallace,  they  do  not  contain  any  Mesozoic  or 
Palaeozoic  rocks,  being  mostly  volcanic.  Hence  he  concludes 
that  these  islands  must  be  of , modern  origin.  How  illusive 
this  conception  is  may  be  gathered  from  Dr.  Blanford'sf  re- 
marks on  this  subject:  "  If  Africa,  south  of  the  Atlas,  sub- 
sided 2,000  fathoms,  what  would  remain  above  water?  So 
far  as  ,our  present  knowledge  goes,  the  remaining  islands 
would  consist  of  four  volcanic  peaks,  th©  Camaroons,  Mount 
Kenia,  Kilimanjaro,  and  Stanley's  last  discovery,  Kuwenzori, 
together  with  an  island,  or  more  than  one,  containing  part  of 
the  Abyssinian  tableland,  which,  like  the  others,  would  be 
composed  of  volcanic  rocks,  but,  unlike  them,  would  consist  of 
horizontal  or  nearly  horizontal  lava  flows,  probably  of 
of  Mesozoic  age.  In  southern  Africa,  too,  the  peaks  of  the 
Stormberg  and  Drakensberg,  though  not  rising,  or  scarcely 
rising  above  10,000  feet,  are  the  highest  in  the  country  and 
consist  of  volcanic  rocks.  The  same  is  the  case  with  the 
highest  peaks  in  Madagascar,  in  Mexico,  in  the  Caucasus,  in 
the  Elbruz  chain  south  of  the  Caspian,  and  in  many  other 
parts  of  the  world ;  though  the  case  of  Africa  is  perhaps 
the  most  remarkable." 

The  question  whether  all  the  numerous  oceanic  islands  that 
are  scattered  about  the  Pacific  and  Atlantic  Oceans  are  really 
modern  volcanic  products  or  of  recent  organic  origin,  has 
also  received  some  attention  recently.  According  to  Dr. 
Arldt,J  Archaean  rocks  have  been  noticed  on  the  Solomon 
islands,  gneiss  and  allied  rocks  occur  on  the  New  Hebrides 
and  New  Caledonia,  while  even  from  the  Marquesas  have 
been  recorded  ancient  rocks. 

So  far  I  have  discussed  only  a  very  small  portion  of  the 
purely  zoological  aspect  of  the  trans -Atlantic  land  connection 

*  Gregory,  J.  W.,  "  Geology  of  the  West  Indies,"  p.  307. 
t  Blanford,  W.  T.,  "  Anniversary  Address,"  pp.  34—35. 
J  Arldt,  Th.,  "  Entwicklung  der  Kontinente,"  pp.  457—458. 


278  ORIGIN   OF   LIFE   IN   AMERICA 

problem.  This  problem  has  been  approached  from  many 
other  points  of  view.  On  the  evidence  of  the  fossil  marine 
mollusks  of  the  West  Indian  and  the  Mediterranean  regions, 
Mr.  Guppy*  concluded  that  a  migration  must  have  taken  place 
right  across  the  Atlantic  along  an  ancient  shore-line.  More 
recently,  Professor  Gregoryf  dwelt  upon  the  intimate  affini- 
ties that  exist  between  the  fossil  sea-urchins  of  the  West 
Indian  and  Mediterranean  areas,  and  urged  that  it  could  only 
be  explained  by  the  assumption  of  a  belt  of  shallow  water 
across  the  Central  Atlantic  in,  at  latest,  Miocene  times.  A 
few  years  later  he  adduced  evidence  from  the  fossil  corals  of 
Barbados,  that  the  West  Indian  fauna  is  only  a  fragment 
of  that  of  the  Mediterranean  Miocene,  having  received 
nothing  from  the  Pacific.  That  this  fauna  did  not  follow 
along  the  shores  of  the  North  Atlantic  basin  is  shown 
by  its  absence  from  the  northern  Miocene  of  Europe  and 
America.}  Mr.  Guppy  §  has  lately  renewed  the  discussion  of 
this  subject  and  once  more  affirmed  his  adherence  to  the 
theory  he  expressed  long  ago,  which  has  meanwhile  received 
so  much  additional  support.  Even  the  recent  marine  fauna  of 
the  Antilles  is  intimately  related  to  that  of  the  Mediterranean. 
Some  of  the  faunistic  marine  affinities  between  the  two  re- 
gions referred  to  might  just  as  well  have  been  produced  by  a 
dispersal  along  a  land  bridge  between  Africa  and  South 
America.  Such,  for  instance,  is  the  occurrence  in  early  Ter- 
tiary deposits  of  the  aquatic  snake  Pterosphenus  in  Egypt 
and  Alabama.  Dr.  Andrews, ||  indeed,  thought  it  yielded  an 
argument  in  favour  of  the  more  southern  land  connection. 

Let  us  now  examine  what  light  the  recent  marine  mammals 
inhabiting  the  Caribbean  Sea  and  the  Gulf  of  Mexico  throw  on 
the  problem.  On  the  south-east  coast  of  Florida  we  meet  with 
one  of  the  most  curious  of  American  mammals.  With 
its  seal-like  head  and  flattened  tail  it  is  at  once  recognised  as 
something  quite  distinct  from  other  marine  creatures.  The 

*  Guppy,  E.  J.  L.,  "  West  Indian  Geology,"  p.  501. 
t  Gregory,   J.   W.,    "  American    and    European    Echinoid    faunas," 
pp.  101—108. 

t  Gregory,  J.  W.,  "  Geology  of  the  West  Indies,"  p.  307. 

§  Guppy,  E.  J.  L.,  "  Geological  Connexions  of  the  Caribbean  Eegion." 

II  Andrews,  C.  W.,  "  Tertiary  Vertebrates  of  the  Fayum,"  p.  xxv. 


MAEINE   MAMMALS  279 

manatee  (Trichechus  manatus),  as  it  is  called,  does  not  in- 
habit the  open  ocean.  It  frequents  shallow  bays  and  lagoons, 
where  it  browses  peaceably  on  seaweeds,  just  as  cattle  graze 
on  land.  This  northern  manatee  lives  also  near  the  coasts 
of  Cuba,  Haiti,  Jamaica  and  other  islands,  as  well  an  along  the 
shores  of  Central  America  and  northern  and  eastern  South 
America.  Curiously  enough,  a  second  species  (Trichechus 
inunguis)  seems  to  be  confined  to  the  upper  reaches  of  the 
Orinoco  and  the  river  Amazon.  Still  more  remarkable  is 
the  fact  that  a  third  species  (Trichechus  senegalensis)  is 
confined  to  the  coasts  and  rivers  of  West  Africa,  for 
since  the  open  ocean  is  to  the  manatees  just  as  much1 
a  barrier  to  migration  as  it  is  to  terrestrial  mammals,  the 
distribution  of  these  manatees  implies  the  existence  of  a 
former  shore-line  across  the  Atlantic.  It  is  quite  true  thait 
in  early  Tertiary  times  manatees  have  lived  much  further 
north  than  they  do  now,  but  the  European  ones,  at  any  rate, 
belonged  to  different  genera  from  those  now  living.  We 
possess  no  evidence,  therefore,  for  the  supposition  that  the 
ancestors  of  the  American  species  passed  along  the  eastern 
shores  of  North  America  and  crossed  to  northern  Europe 
along  the  ancient  Greenland-Iceland  land  bridge,  thus  even- 
tually reaching  Africa.  Another  theory,  even  less  probable 
I  think,  is  that  suggested  by  Professor  Osborn.*  He  thought 
a  migration  might  have  taken  place  from  Africa  by;  way  of 
the  Pacific  coasts  of  Asia  and  North  America,  the  ancestors 
of  the  West  Indian  manatees  entering  the  Atlantic  through  a 
strait,  which  is  supposed  to  have  connected  that  ocean  with 
the  Pacific,  in  mid-Tertiary  times.  He  considers  this  cir- 
cuitous route  a  more  probable  one  than  the  trans -Atlantic  one. 
Yet  he  does  not  clearly  explain  how  the  close  relationship 
between  the  West  African  and  eastern  South  American  forms 
was  brought  about. 

This,  however,  by  no  mean  completes  all  the  evidence  de- 
rived from  the  manatees  in  favour  of  the  theory  of  a  trans- 
Atlantic  land  -bridge.  Dr.  Dilg  f  has  pointed  out  that  the 
molar  teeth  of  the  adult  living  manatees  resemble  those  of 

*  Osborn,  H.  F.,  "  Age  of  Mammals,"  pp.  493—494. 

t  Dilg,  Carl,  "  Morphologic  des  Schadels  bei  Manatus,"  p.  139. 


280  ORIGIN   OF   LIFE   IN   AMERICA 

the  Eocene  Prorastomus,  which  must  be  looked  upon  as  the 
ancestor  of  Trichechus.  I  mentioned  before  that  Proras- 
tomus has  been  discovered  in  the  Eocene  of  Jamaica.  The 
teeth  of  another  form  (Prorastomus  veronensis)  are  1m own 
from  Italy.  Thus  the  affinity  still  existing  between  the  South 
American  and  West  African  forms  was  apparently  fore- 
shadowed already  during  the  Eocene  Period  by  the  relation- 
ship of  the  two  species  of  Prorastomus,  the  ancestors  of  thev 
modern  manantees.  Dr.  Smith  Woodward,  however,  informs 
me  that  the  relationship  of  these  species  is  too  uncertain  to  be 
used  as  evidence  in  favoutfof  an  Eocene  land  bridge. 

All  the  seals  inhabiting  the  North  Atlantic,  both  on  the 
European  and  North  American  side,  belong  to  the  genera 
Halichoerus  or  Phoca.  As  soon  as  we  enter  the  Antillean 
region  these  genera  disappear,  their  place  being  taken  by  the 
genus  Monachus.  On  the  opposite  shores  of  Europe  it  is  just 
the  same.  As  far  south  as  Portugal  we  still  find  the  common 
seals,  but  as  we  enter  the  Mediterranean  we  again  meet  with 
the  same  genus  Monachus.  The  Antillean  form  (Monachus 
tropicalis),  like  the  Mediterranean  Monachus  albiventer, 
seems  to  be  on  the  verge  of  extinction.  The  former  was  once 
common  off  Florida  and  near  most  of  the  islands.  Now  it  is 
only  noticeable  in  the  neighbourhood  of  Cuba  and  some  of  the 
islands  near  Yucatan.  We  can  hardly  believe,  remarked 
Messrs.  Sclater,*  that  these  creatures  could  easily  traverse 
the  whole  Atlantic.  The  hypothesis  of  a  former  barrier  of 
land  between  Africa  and  America,  which  we  know  to  be  sup- 
ported by  other  facts  of  distribution,  would  alone  explain  the 
difficulty,  according  to  these  authors.  They  only  had  the  sup- 
posed land  connection  between  Africa  and  South  America  in 
mind,  but  what  strengthens  the  evidence  in  support  of  another 
more  northerly  mid-Atlantic  land  bridge  between  the  Antilles 
and  the  Mediterranean  region  is  the  fact  that  the  only  locali- 
ties outside  the  Mediterranean  where  Monachus  albiventer 
occurs  are  on  the  coasts  of  Madeira  and  the  Canary  islands. 

Among  the  terrestrial  species  of  vertebrates  and  inverte- 
brates of  the  Antilles,  as  I  observed,  the  affinity  with  Europe 
is  less  marked  perhaps  than  it  is  in  the  south-western  States 

*  Sclater,  W.  L.,  and  P.  L.  Sclater,  "  Geography! of  Mammals,"  p.  217. 


FIG.  14. — Map  of  North  and  South  America,  indicating  roughly  the  supposed 
conditions  of  land  and  water  about  the  commencement  of  the  Tertiary  Era. 
The  ancient  land  is  slightly  tinted. 


[To  face  p.  280. 


MID-ATLANTIC   LAND   BRIDGE  281 

of  North  America.  I  explained  this  by  the  supposition  that 
the  widespread  submergence  of  the  Antilles  destroyed  most  of 
the  immigrants  from  Europe.  It  ought  not  to  have  affected 
the  emigrants  to  Europe  from  the  Antilles  to  the  same  extent, 
I  mean  those  forms  which  spread  from  the  Antillean  centre, 
because  they  would  have  had  more  time  to  adapt  themselves 
to  the  more  elevated  regions  in  the  West  Indies,  and  would 
thus  have  had  more  chance  of  .surviving  the  submergence 
which  did  not  entirely  cover  the  islands. 

One  of  the  most  noteworthy  examples  of  that  kind,  though 
not  a  very  conspicuous  onq,  is  the  newt  Spelerpes.  [  alluded1 
to  its  range  in  North  America  on  several  occasions  (pp.137 — 
138  and  p.  221),  pointing  out  that  its  headquarters  were  in 
Mexico,  while  a  single  species  had  succeeded  in  reaching  the 
Mediterranean  region.  We  may  assume,  therefore,  that 
certain  members  of  the  old  American  Spelerpes  stock 
emigrated,  in  early  Tertiary  or  even  in  Mesozoic  times,  by 
means  of  the  trans -Atlantic  land  bridge,  that  extended  from 
the  Antilles  to  a  land  area  which  covered  part  of  the  western 
Mediterranean  (Fig.  14).  That  Spelerpes  long  ago  existed  all 
over  the  Antilles  is  indicated  by  the  fact  that  a  single  species 
(Spelerpes  infuscatus)  still  inhabits  the  island  of  Haiti. 

Another  instance  I  alluded  to  (p.  173)  in  support  of 
the  mid- Atlantic  land  bridge  theory,  is  the  glass -snake 
family  (Anguidae).  The  genus' Ophisaurus,  w'hich  is  found 
in  the  Mediterranean  region,  does  not  occur  on  the  Antilles, 
but  several  species  are  known  from  the  mainland  of  North 
America.  The  genus  Anguis  is  quite  confined  to  Europe, 
western  Asia  and  north  Africa.  On  the  other  hand,  numerous 
relations  live  in  the  West  Indies.  Sauresia  and  Panolopus  are 
confined  to  Haiti,  whereas  Celestus  (Diploglossus)  inhabits 
Portorico,  Haiti,  Jamaica,  Cuba,  Central  America,  Mexico 
and  northern  South  America.  The  headquarters  of  the 
Anguidae  certainly  are  in  the  West  Indies  and  Central 
America,  and  it  is  from  there  that  they  must  have  spread  to 
Europe  and  beyond,  as  far  as  the  Himalayas,  when  a  land 
bridge  across  the  Atlantic  permitted  them  to  do  so. 

Let  us  now  return  to  the  investigation  of  the  geological 
history  of  the  Antillean  area.  Among  the  vertebrates,  the 
mammals  perhaps  are  of  the  greatest  importance,  in  so  far 


282  ORIGIN   OF   LIFE   IN   AMERICA 

as  they  are  not  supposed  to  be  subject  to  accidental  dispersal. 
The  West  Indian  mammals  *  consist  of  a  mixture  of  exceed- 
ingly ancient  and  of  apparently  much  more  modern  types,  and 
yet  all  are  distinct  enough  from  mainland  forms  to  exclude  the 
idea  of  recent  land  connections  of  the  Greater  Antilles  either 
with  Central  America  or  the  two  neighbouring  continents. 

The  most  ancient  mammal  found  in  the  West  Indian 
islands  is  the  curious  insectivore  Solenodon.  It  is  the  sole 
genus  of  the  family  Solenodontidae,  whose  nearest  living 
relations  are  the  Centetidae  of  Madagascar  and  West  Africa. 
The  two  Antillean  forms  (S.  paradoxus  and  S.  cubanus)  f  are 
in  general  quite  similar.  Yet  they  differ  somewhat  in  size, 
colour  and  dentition,  as  well  as  in  the  shape  of  the  skull,  and 
for  that  reason  are  perfectly  distinct  species.  The  first  is  con- 
fined to  Haiti,:  the  other  to  Cuba.  Professor  Leche  J  expresses 
the  view  that  Madagascar  lost  its  continental  land  connection 
already  during  the  Eocene  Period.  Hence  the  Centetidae  may 
be  of  early  Tertiary  or  even  Mesozoic  age.  Professor  Leche 
believes  in  a  former  land  connection  between  Madagascar  and 
Africa,  and  in  another  between  Africa  and  Brazil.  Both  of 
these  must  have  existed  about  the  same  time,  and  they  were 
used  presumably  by  the  ancestors  of  the  Centetidae  and 
Solenodontidae  in  passing  from  Madagascar  to  South 
America,  and  thence  to  the  West  Indies,  or  vice  versa. 

The  only  large  West  Indian  mammals,  Capromys  and 
Plagiodontia,  belong  to  the  rodents.  The  hutias,  as  they  are 
called,  remind  us  somewhat  of  the  great  rat-like  South 
American  coypu,  but  the  tail  is  longer  and  they  possess 
arboreal  habits  and  certain  structural  characters  differing 
from  the  latter.  The  two  genera  of  hutia  are  quite  confined 
to  the  West  Indies.  Three  species  of  Capromys  are  known 
from  Cuba,  one  from  the  Bahamas  and  one  from  Jamaica. 
Still  another  Capromys  inhabits  the  small  Swan  island,  in  the 
Gulf  of  Honduras,  mid-way  between  Jamaica  and  Central 
America.  Nevertheless,  the  genus  is  quite  unknown  from  the 
mainland.  The  other  genus  (Plagiodontia)  only  occurs  on 

*  Allen,  Glover  M.,  "Mammals  of  West  Indies."  (This  work  was 
received  too  late  for  discussion.) 

t  Allen,  J.  A.,  "Notes  on  Solenodon  paradoxus,"  pp.  507 — 515. 
t  Leche,  W.,  "  Centetidae,  Solenodontidae,  &c.,"  pp.  132—139. 


MAMMALS   OF  WEST   INDIES  283 

Haiti.  Of  the  past  history  of  these  hutias  we  only  know 
that  one  extinct  species  (Capromys  columbianus)  has  been 
discovered  in  the  Pleistocene  deposits  of  Cuba.  The  only  near 
relation  living  is  Procapromys  geayi,  from  the  neighbourhood 
of  -Caracas  in  the  mountains  of  Venezuela,.  This  implies 
southern  affinities  of  the  genera  Capromys  and  Plagiodontia. 
Proceeding  further  south  in  search  of  their  possible  ances- 
tors we  meet  with  another  nearly  related  genus  (Matyoscor) 
in  the  Pleistocene  of  Bolivia.  Still  further  south  we  find 
on  some  of  the  islands  of  the  Chilean  coa,st,  as  well  ais  in  Chile, 
Peru  and  Argentina,  the  coypu  (Myocastor  coypus),  already 
alluded,  to  as  resembling  the  hutias.  Finally,  in  the  Pliocene, 
Miocene  and  Eocene  beds  of  Patagonia,  various  ancestral 
types  of  these  modern  forms  have  been  discovered  by  Pro- 
fessor Ameghino.  Thus  the  available  evidence  points  to  a 
remote  Patagonian  origin  of  the  hutias.  The  question  then 
arises,  have  the  ancestors  of  these  West  Indian  mammals 
proceeded  northward  through  eastern  or  western  South 
America  ?  The  testimony  we  possess  is  distinctly  in  favour 
of  the  latter  theory,  though  it  is  mainly  of  a  negative  cha- 
racter. In  the  west  we  have  the  living  coypu  and  the  extinct 
Matyoscor,  while  the  former  has  only  invaded  Brazil  in  recent 
geological  times.  The  Venezuelan  Procapromys  might  lead 
us  to  'believe  that  the  ancestors  of  the  hutias  had  gained 
admittance  to  the  Antillean  region  by  an  old  land  connection 
across  the  lesser  Antilles.  But  since  no  trace  of  the  former 
presence  there  of  any  coypu -like  mammal  has  been,  dis- 
covered, and  as  a  species  of  hutia  exists  on  Swan  island,  the 
hypothesis  that  the  ancestors  of  these  mammals  reached  the 
West  Indies  directly  from  some  western  lands  seems  to  me  the 
most  probable. 

Except  the  Bahama  raccoon  (p.  181)  and  a  species  of 
opossum  (Didelphys  marsupialis),  which  inhabits  the  islands 
of  Trinidad,  Dominica,  Grenada  and  St.  Vincent,  all  other 
Antillean  mammals  are  small  and  inconspicuous.  The 
raccoon  may  possibly  be  very  ancient,  but  we  know  too  little 
about  its  geological  history  to  enable  us  to  speculate  on 
its  origin  in  the  Bahama  islands.  The  presence  of  the 
opossum  on  some  of  the  Lesser  Antilles  seems  to  indicate 
that  they  had  been  connected  with  one  another  and  with  Vene- 


284  ORIGIN   OF   LIFE   IN   AMERICA 

zuela  within  comparatively  recent  geological  times,  a  con- 
clusion which  perfectly  agrees  with  the  results  obtained  from 
other  faunistic  evidence. 

The  groups  of  smaller  mammals  which  have  representa- 
tives in  the  West  Indies  are  the  rice-rats  (Oryzomys)  and 
the  musk-bearing  rats  (Moschophoromys=Megalornys).  Like 
the  hutias  and  solenodons,  the  latter  are  confined  to  this 
region,  but  they  are  only  known  from  the  Lesser  Antilles, 
Moschophoromys  desmaresti  being  peculiar  to  Martinique, 
whereas  M.  luciae  is  only  found  on  St.  Lucia.  The  occurrence 
of  this  peculiar  genus  of  small  mammals  on  the  Lesser 
Antilles  implies  that  their  connection  with  the  mainland  must 
be  of  longer  standing  than  is  generally  supposed.  The 
opossum  (Didelphys  marsupialis),  is  one  of  the  few  species 
of  terrestrial  mammals  having  a  wide  range  in  both  North 
and  South  America,  and  must,  therefore,  be  considered  as 
a  persistent  specific  type  of  great  antiquity.  It  may  possibly 
have  retained  its  specific  characters,  while  the  ancestors  of 
the  musk-bearing  rats  rapidly  became  modified  on  the  islands. 
That  the  latter  are  not  recent  introductions  is  likewise  in- 
dicated by  the  fact  that  an  extinct  species  of  Moschophoromys 
is  known  from  Barbados. 

The  rice-rats  (Oryzomys)  inhabit  both  the  islands  and  the 
mainland.  Their  very  wide  and  discontinuous  range  in  North 
and  South  America  at  once  suggests  an  ancient  origin.  One 
species  (0.  antillarum)  was  so  abundant  in  Jamaica,  and  did 
such  damage  to  the  crops,  that  the  mongoose,  a  small  carni- 
vore, was  imported  from  India  for  its  destruction.  For  a 
time  the  experiment  appeared  to  be,  quite  successful.  After 
some  ten  years,  however,  when  the  rice-rats  became  scarce, 
the  mongoose  began  to  pay  attention  to  snakes,  lizards, 
tortoises  and  birds.  As  it  developed  a  taste  for  them  they 
in  their  turn  became  scarce,  until  it  was  found  that 
the  mongoose  was  worse  than  any  other  animal  pest,  forx 
owing  to  the  great  destruction  of  the  useful  members  of 
the  fauna,  insects  and  ticks  had  increased  to  an  alarming 
extent.  The  disturbance  of  the  due  balance  of  nature  by 
man  is  always  risky,  and  thus  sometimes  leads  to  incalculable 
damage. 

A  second  species  of  rice-rat  (0.  victus)  is  peculiar  to  the 


FOSSIL  MAMMALS   OF  WEST   INDIES        285 

Lesser  Antilles.  A  few  others  live  in  Trinidad.  It  is  im- 
probable that  Jamaica  was  at  any  time  connected  by  land 
with  the  Lesser  Antilles,  independently  of  the  larger  islands. 
It  is  possible,  therefore,  that  the  genus,  being  mainly  South 
and  Central  American,  entered  the  Antilles  in  two  independent 
streams,  one  from  the  south,  the  other  from  the  west.  This 
may  have  taken  place  when  the  other  large  islands  had  already 
become  isolated  from  Jamaica. 

We  have  still  to  consider  the  remains  of  some  extinct 
mammals  which  have  been  traced  in  the  Antilles.  To  judge 
from  recent  cave  researches  in  Cuba,  we  are  only  now  begin- 
ning to  acquire  a  knowledge  of  the  past  history  of  this  fauna, 
though  certain  indications  enable  us  to  speculate  as  to  its 
general  nature  and  origin.  Dr.  Spencer  *  alludes  to  the  dis- 
covery in  a  Cuban  cave  of  large  edentate  remains  belong- 
ing to  Myomorphus  cubensis.  This  creature,  which  Dr. 
Matthew  informs  me  is  now  known  as  Megalocnus,  was  about 
the  size  of  a  small  bear,  being  a  peculiar  aberrant  specializa- 
tion apparently  derived  from  some  Miocene  (Santa  Cruz) 
ground  sloth.  Professor  Ameghino  f  describes  a  new  species 
of  man  (Homo  cubensis)  from  a  cave  in  Cuba;  and  from  a 
{preliminary  report  read  at  the  International  Congress  of 
Geology  at  Stockholm  by  Professor  de  la  Torre,  we  are  led  to 
infer  that  other  edentates,  and  also  several  kinds  of  rodents, 
lived  on  this  island  within  comparatively  recent  geological 
times.  Dr.  Matthew  writes  to  me  that  the  mammalian  re- 
mains from  Cuba  sent  to  the  American  Museum  of  New  York 
are  awaiting  determination.  Dr.  Spencer  J  also  makes  refer- 
ence to  several  large  species  of  rodents  of  the  genus  Amblyr- 
hiza  which  were  found  in  the  phosphate  beds  of  the  small 
island  of  Anguilla.  The  Amblyrhiza  remains  are  now  thought 
to  belong  to  a  single  species  (A.  inundata),  closely  related  to 
Castoroides,  a  giant  beaver,  which  made  its  first  appearance 
in  North  America  during  the  Pleistocene  Period.  The  former 
presence  in  Anguilla  and  Cuba  of  large  mammals  naturally 
suggests  that  these  islands  had  some  continental  connection. 
Dr.  Spencer,  indeed,  quotes  these  fossils  in  support  of  the 

*  Spencer,  J.  W.,  "  Antillean  Continent,"  pp.  128—138. 
t  Ameghino,  Fl.,  "  Nueva  especie  del  g6nero  Homo,"  p.  5. 
t  Spencer,  J.  W.,  "Fossil  Mammals  in  Cuba,"  pp.  512 — 513. 


286  ORIGIN   OF   LIFE  IN   AMERICA 

theory,  largely  based  on  the  supposed  drowned  valleys  of  the 
Antillean  area,  that  the  two  American  continents  were  united 
with  one  another  by  means  of  a  West  Indian  land  bridge 
during  the  Pleistocene  Period.  He  thought  this  land  must 
have  had  the  enormous  altitude  of  from  8,000  to  12,000  feet. 
Against  this  view  it  may  be  urged  from  a  general  faunistic 
study  that  such  a  land  bridge  is  out  of  the  question, 
because  the  Antillean  fauna  would  be  quite  different  from 
what  it  actually  is.  A  very  small  part  of  southern  Florida 
may  have  been  still  joined,  by  way  of  the  Bahamas,  to  Cuba 
and  Anguilla  in  Pliocene  times.  But  southern  Florida  must 
then  have  been  separated  from  North  America  by  a  marine 
channel.  Nor  could  there  have  been  any  junction  of  the 
greater  Antillean  land  with  South  America,  by  means  of  the 
Lesser  Antilles,  at  any  time  during  the  Tertiary  Era.  In  all 
probability  the  West  Indies,  while  still  partly  united  with  one 
another,  had  some  kind  of  land  connection  with  Central 
America,  while  the  latter  was  cut  off  by  the  sea  from  both 
North  and  South  America.  Hence  the  mammalian  supply  came 
mostly  from  the  west.  Still,  it  may  be  asked,  how  did  this 
fauna  reach  Central  America  ?  Almost  all  the  Antillean  mam- 
mals, both  recent  and  extinct,  can  be  traced  to  a  southern 
ancestry,  except  Castoroides,  of  which  we  only  know  that  it 
appeared  in  the  north  along  with  a  host  of  southern  invaders. 
I  believe  the  cause  of  the  mystery  connected  with  the  occa- 
sional entrance  during  various  periods  in  Tertiary  times  of 
South  American  forms  into  North  America  is  now  buried 
beneath  the  waves  far  out  in  the  Pacific  Ocean  (see  Fig.  14). 
I  have  frequently  suggested  the  theory  that  a  large  land 
eurface,  mainly  tenanted  by  a  South  American  stock,  lay 
westward  of  Central  America.  A  good  deal  of  the  next 
chapter  will  be  devoted  to  its  consideration.  Meanwhile, 
I  can  only  state  my  conviction  that  the  animals  alluded  "to, 
and  many  others,  had  their  origin  on  that  western  Pacific 
land  whence  they  streamed  into  the  neighbouring  continents 
whenever  physical  conditions  offered  an  opportunity  for 
doing  so. 

The  main  conclusion  which  this  brief  study  of  the  mam- 
malian fauna  of  the  Antilles  has  revealed  is  that  the  larger 
islands  were  formerly  united  with  one  another,  and  with  the 


ELEVATION   OF   WEST   INDIAN   AREA         287 

Bahamas,  by  land.  How  far  eastward  this  land  extended 
cannot  be  determined  from  the  mammals,  but  it  certainly 
must  have  reached  beyond  the  Virgin  islands  to  Anguilla,  one 
of  the  most  northerly  islands  of  the  Lesser  Antilles.  Many 
islands  of  the  Lesser  Antilles  may  have  been  completely 
submerged  at  that  time.  Later  on  Cuba,  the  Bahamas  and 
Jamaica  were  connected  with  the  mainland,  after  the  other 
islands  had  already  been  separated  from  the  Antillean  land- 
mass,  and  lastly,  Cuba  and  Jamaica  were  independently  joined 
to  Central  America  before  the  existing  physical  features  were 
brought  about. 

Many  more  details  are  required  before  we  can  construct 
an  approximate  history  of  the  geological  events  which  led  to 
the  present  conditions  of  the  fauna  and  flora  of  the  Antilles. 
In  his  chapter  on  the  evolution  of  middle  America  Dr. 
Gadow  *  deals  with  the  problem  from  the  aspect  of  the 
reptilian  and  amphibian  fauna.  He  does  not  attempt  to  recon- 
struct the  geological  history  from  a  study  of  this  fauna  alone. 
His  maps  are  derived  and  abstracted  from  the  opinions  ex- 
pressed by  various  geological  authorities.  They  are  in  so  far 
of  importance,  as  he  thinks,  that  the  general  conclusions 
based  on  a  geological  study  appear  to  fit  those  founded  on 
faunistic  considerations.  Several  striking  points  may  be 
gathered  at  a  glance  from  his  maps.  At  no  time  since  the 
Cretaceous  Period  were  the  Antilles  directly  connected  with 
the  main  continent  of  North  America.  Only  in  Miocene  times 
was  "  Antillea"  (the  term  used  for  the  united  Antilles)  joined 
to  southern  Florida,  the  latter  being  then  disconnected  from 
North  America.  Antillea  had  only  one  continental  connec- 
tion, namely,  during  the  Miocene  Period  by  means  of  Central 
America.  It  follows,  therefore,  that  Antillea  never  was  directly 
joined  either  to  North  or  South  America,  at  least  not  since 
Cretaceous  times.  If  Dr.  Gadow's  maps  are  correct,  the  whole 
of  the  Antillean  fauna  and  flora,  in  so  far  as  they  are  derived 
from  migration  on  land,  should  be  of  Miocene  age  or  older. 
Dr.  Gadow's  conclusions  would  have  been  of  greater  value  had 
he  trusted  more  to  the  evidence  based  on  geographical  dis- 
tribution and  less  on  that  of  geology.  As  pointed  out  by 

*  Gadow,  H.,  "  Mexican  Amphibians  and  Eeptiles,"  pp.  234—237, 


288  ORIGIN   OF   LIFE   IN   AMERICA 

Dr.  Stejneger,*  a  few  Antillean  genera,  such  as  Ameiva, 
Amphisbaena,  Typhlops  and  Alsophis,  possess  a  (Southern  rela- 
tionship. The  species  of  burrowing  snake,  Typhlops  lumbri- 
calis,  is  even  confined  to  the  West  Indies  and  British  Guiana 
without  entering  Central  America.  Dr.  Stejneger  does  not 
actually  speak  of  a  former  land  connection  of  Antillea  with 
South  America,  but  I  explained  above  that  some  geologists 
advocate  an  ancient  union  of  the  two  continents  by  way  of 
the  Lesser  Antilles.  If  such  a  connection  existed,  I  think 
it  must  have  been  in  the  pre-Cretaceous  times.  Most  zoo- 
logists would  deride  the  idea  of  any  terrestrial  species 
having  been  transmitted  to  us  unchanged  from  pre-Cretaceous 
times  to  the  present  day.  We  have  no  geological  evidence  of 
such  a  fact,  but  Dr.  Sarasin  expresses  the  opinion  that  the 
genus  Typhlops,  at  any  rate,  is  older  than  the  Cretaceous 
Period.  We  gather  from  Dr.  Stejneger's  researches  that  the 
great  majority  of  the  Portorican  species  are  western  in  their 
affinities,  and  that  Portorico  and  the  more  easterly  Virgin 
islands  certainly  must  have  been  connected  with  one  another 
in  comparatively  recent  geological  times. 

As  regards  Jamaica,  Mr.  Barbour  gives  us  some  interesting 
details  as  to  its  reptiles  and  amphibians.  He  emphasises  the 
fact,  which  I  have  already  alluded  to  in  speaking  of  the 
mammals  (p.  285),  that  the  distinctive  characters  of  this 
island  are  not  shared  by  the  rest  of  the  Antilles^Jamaica  is 
related  faunistically  to  Central  America  and  Haiti,  while  the 
relationship  with  Cuba  is  much  more  remote/  Mr.  Barbour 
thinks  that  the  early  separation  of  Jamaica  from  the  main- 
land and  from  Haiti  would  account  for  the  absence  of  types 
having  such  a  distribution  as  Bufo  and  Amphisbaena,  which 
may  have  reached  Haiti  from  Central  America  by  way  of 
Cuba.  If  fortuitous  dispersal  has  played  practically  no  part  in 
providing  the  Antilles  with  a  fauna,  as  Mr.  Barbourf  is  in- 
clined to  think,  the  Bahamas  certainly  must  have  belonged  to 
Antillea  and  cannot  have  been  submerged  since.  Sixteen 
species  of  reptiles  and  amphibians  are  described  by  Mr. 
BarbourJ  as  occurring  in  the  Bahaman  archipelago.  Several 

*  Stejneger,  L.,  "  Herpetology  of  Porto  Eico,"  pp.  561—563. 
t  Barbour,  Thomas,  "  Herpetology  of  Jamaica."  pp.  277 — 285. 
t  Harbour,  Thomas,  "Batrachia  and  ReptiJia  of  Bahamas." 


ANCIENT   LAND   CONNECTIONS  289 

of  these  are  peculiar  to  the  group.  And  yet  in  spite  of  this 
feature,  in  spite  of  the  fact  that  two  kinds  of  mammals  live  on 
the  islands,  and  that  numerous  mollusks  and  other  inverte- 
brates are  quite  confined  to  the  Bahamas,  we  often  read  the 
statement  that  the  fauna  of  these  islands  is  entirely  a  product 
of  accidental  transport  by  winds,  waves  or  human  agency. 

How  little  influenced  the  Antilles  are  by  accidental  intro- 
ductions is  well  shown  by  a  study  of  such  groups  as  the 
dragon-flies  and  their  allies  (Neuroptera  and  Pseudoneu- 
roptera),  and  the  butterflies  and  moths  (Lepidoptera).  If 
winds  played  any  active  part  in  their  dispersal,  we  should 
find  many  species  from  North  America  in  the  Greater  Antilles, 
whereas  the  affinities  agree  almost  precisely  with  those  of 
the  other  animals  already  considered.  Several  genera  of 
dragon-flies,  known  both -from  North  and  South  America,  such 
as  Chauliodes,  Corydalis,  Mantispa  and  others,  are  wanting 
in  the  West  Indian  islands,  thus  showing  that  the  migration 
between  the  two  continents  did  not  take  place  across  the 
Antillean  area.  The  great  majority  of  the  genera  are  South 
or  Central  American.  Only  two  genera  of  dragon-flies  ,are  con- 
fined to  the  Antilles.  On  the  other  hand,  many  continental 
ones  are  absent.  The  Lesser  Antilles  contain  some  South 
American  species  which  are  wanting  in  the  Greater  Antilles.* 
Similarly  the  Lepidoptera  exhibit  affinities  with  northern 
South  America,  Central  America  and  Florida.  Several  cha- 
racteristically southern  families,  nevertheless,  are  wanting  in 
the  Antilles.  The  four  large  islands  are  characterised  by  the 
absence  of  many  neotropical  genera,  and  the  presence  of  a 
genus  and  many  species  that  are  peculiar  to  them.  Jamaica 
shows  some  special  features  of  interest. f 

The  birds  exhibit  similar  peculiarities  in  their  geographical 
distribution.  One  whole  family,  the  todies  (Toditae),  are  con- 
fined to  the  larger  islands  of  Cuba,  Jamaica,  Haiti  and  Por- 
torico.  They  bear  a  certain  resemblance  to  the  kingfishers, 
but  differ  in  colour,  whereas  in  habits  and  shape  of  bill  they 
resemble  the  flycatchers.  In  reality  they  are  related  to  the 
Central  American  motmots.  We  also  have  the  same  striking 

*  Kolbe,  H.  J.,  "  Neuroptera  und  Pseudoneuroptera  d.  Antillen," 
pp.  154—161. 

t  Pagenstecher,  A.,  "  Verbreitung  der  Schmetterlinge,"  pp.  391 — 394. 
L.A.  U 


290  OEIGIN   OF   LIFE   IN   AMERICA 

number  of  absentees  and  peculiar  species  among  the  birds, 
as  in  other  groups.  Dr.  Chapman*  is  evidently  puzzled  how 
to  account  for  the  avifauna.  Nevertheless,  he  makes  the 
remarkably  suggestive  statement  that  if  it  could  be  shown 
that  Central  America  was  cut  off  from  both  continents  at  the 
time  when  it  was  joined  to  the  West  Indies,  the  origin  of  the 
island  fauna  could  be  explained  in  a  satisfactory  manner. 
That  is  precisely,  I  think,  what  did  happen,  as  I  have  indicated 
above. 

Cuba  presents  some  special  aspects  of  interest.    We  have  in 
the  first  instance  quite  a  remarkable  assemblage  of  fossil 
mammals.    Western  Cuba,  with  its  extensive  limestone  dis- 
tricts, abounds  in  caves,  many  of  which  contain  stagnant 
water  or  running  streams.    One  of  the  most  remarkable  fea- 
tures of  these  subterranean  waters  is  that  they  are  tenanted 
by  two  kinds  of  fishes  belonging  curiously  enough  to  a  family 
of  deep-sea  forms   (Brotulidae).      These  species,   Stygicola 
dentatus   and    Lucifuga    subterraneus,  moreover,  are  blind, 
as  might  be  expected  from  their  habitat.     Another  typically 
marine  genus,  Atherina,  possesses  a  single  fresh -water  species 
(A.  evermanni)  which  is  only  known  from  western  Cuba. 
Whether  the  presence  of  these  marine  species  in  fresh  water 
implies  that  western  Cuba  had  been  submerged  below  sea- 
level  is  a  debatable  question  that  need  not  be  further  pur- 
sued.   Other  Cuban  fresh-water  fishes  are  forms  often  found 
in  brackish  water,  or  marine  forms  migrating  into  fresh  water. 
Besides  these  there  are  two  species  of  Heros,  a  Symbranchus, 
a  Lepidosteus  and  one  Agonostomus,  all  of  which  belong  to 
purely  fresh -water  groups  that  could  only  have  reached  Cuba 
by  means  of  a  continuous  system  of  lakes  and  rivers  between 
the  mainland  and  the  island.    Heros  tetracanthus  and  Heros 
nigricans  are  members  of  the  family  Cichlidae,  which  has  a 
wide    range    in    South  and  Central  America,  only  a  single 
species  entering  the  United  States.    Agonostomus  monticola 
has  a  wider  distribution  in  the  West  Indies,  and  is  also  met 
with  in  Mexico.    Lepidosteus  tristoechus  lives  in  Mexico  and 
the  southern  States,  while  Symbranchus  marmoratus  is  widely 
distributed  in  the  fresh  waters  of  tropical  America.     If,  as 

*  Chapman,  F.  M.,  "  West  Indian  Bird  Life,"  p.  330. 


BLIND    ANIMALS   IN   CUBA  291 

geologists  claim,  western  Cuba  has  been  deeply  submerged,  it 
seems  equally  certain  that  it  must  have  been  subsequently 
joined  to  Central  America.  As  Professor  Eigenmann*  re- 
marks, this  Cuban  fauna  has  greater  affinity  with  that  of 
Mexico  than  with  that  of  Florida,  showing  that  the  fishes 
probably  reached  Cuba  by  way  of  Yucatan. 

Western  Cuba  possesses,  among  other  curiosities,  blind 
crustaceans  (Palaemonetes).  They  are  what  we  might  call 
monster  prawns,  and  have  probably  had  marine  ancestors. 
An  allied  species  is  known  from  the  subterranean  waters  of 
Texas.  Faunistically  they  are  not  of  great  importance.  Not 
so,  however,  the  fresh -water  crayfishes,  which  are  justly 
regarded  by  Dr.  Ortmann  f  as  among  the  most  valuable  means 
for  demonstrating  former  changes  of  land  and  water.  All  the 
species  of  Cambarus  but  one  inhabit  either  Mexico  or  the 
United  States.  Only  a  single  crayfish  occurs  in  the  isolated 
position  of  Cuba.  This  species  (C.  cubensis)  is  closely  related 
to  Cambarus  mexicanus,  whereas  the  United  States  species  are 
more  distant  relatives.  Dr.  Ortmann  assumes  on  that 
account  a  former  land  connection  between  Mexico  and  Cuba. 

The  fresh-water  crabs,  as  I  already  indicated,  advanced 
northward  from  the  south,  eventually  invading  the  Central 
American  territory  and  the  West  Indies.  Thus  three  species 
of  Pseudothelphusa  have  been  discovered  in  Cuba.  One  of 
these  (P.  americana)  ranges  from  Mexico  through  Cuba  to 
Haiti.  Another  (P.  terrestris)  is  confined  to  Mexico  and 
Cuba,  while  a  third  (P.  affinis)  is  restricted  to  Cuba.  More- 
over the  genus  Epilobocera  is  peculiar  to  the  Greater 
Antilles,  viz.,  Cuba,  Haiti  and  Portorico,  and  some  smaller 
neighbouring  islands.  A  species  of  Pseudothelphusa  closely 
allied  to  a  Venezuelan  form  is  likewise  known  from  some  of 
the  Lesser  Antilles. 

From  these  facts  Dr.  Ortmann  (pp.  344 — 347)  concludes 
that  the  first  immigration  of  fresh-water  decapods  represented 
by  Epilobocera,  into  the  Greater  Antilles,  belongs  to  the  end 
of  the  Cretaceous  or  the  beginning  of  the  Tertiary  era. 
Cambarus  cubensis,  he  suggests,  possibly  belongs  to  it  also. 

*  Eigenmann,  C.  H.,  "Freshwater  Fishes  of  Cuba,"  pp.  220—221. 
t  Ortmann,  A.  E.,  "Distribution  of  Freshwater  Decapods,"  p.  315. 

u2 


292  ORIGIN   OF   LIFE   IN   AMERICA 

Although  it  is  a  primitive  form,  he  prefers  to  put  its  immigra- 
tion in  the  Tertiary  rather  than  in  the  Cretaceous.  The  history 
and  development  of  the  Central  American  and  West  Indian 
region  he  imagines  to  have  been  as  follows  :  "  Central  America, 
the  West  Indies  and  the  northern  margin  of  South  America, 
formed  in  the  Mesozoic  Period  (certainly  during  the  Jurassic 
and  Cretaceous)  a  continental  mass  (Antillean  Continent), 
which  was  bounded  by  sea  to  the  north  and  south  (Fig.  15). 
This  continent  broke  up  at  the  end  of  the  Cretaceous, 
the  chief  factor  in  its  destruction  being  the  formation 
of  the  Caribbean  Sea.  The  northern  remnant  of  this 
continent,  consisting  of  the  Greater  Antilles  and  parts 
of  the  present  Central  America,  probably  remained  a  unit 
up  to  the  Eocene."  At  the  end  of  the  Eocene,  he 
continues,  and  during  the  Oligocene  and  Miocene  Periods, 
the  connection  between  the  Greater  Antilles  and  the  main- 
land was  severed,  being  subsequently  re-established  toward 
the  end  of  the  Tertiary  Era  (Fig.  20)  and  again  destroyed  in 
recent  times. 

My  own  views  are  in  some  respects  similar  to  those  of  Dr. 
Ortmann,  yet  they  differ  in  a  few  important  points.  If  we 
begin,  say  with  later  Cretaceous  times,  when  a  wide  marine 
channel  still  separated  eastern  from  'western  North  America, 
northern  South  America  was  submerged,  and  could  not  have 
formed  part  of  the  supposed  Antillean  Continent.  Towards 
the  end  of  the  Cretaceous  Period,  all  the  Antilles,  except  the 
Bahamas,  were  entirely  covered  by  the  sea,  according  to  Pro- 
fessor  Schuichert's  paleogeographic  maps  (Map  95).  Yet 
although  the  peninsula  of  Yucatan  was  then  submerged,  no 
deposits  of  this  age  are  known  from  Guatemala  or  Honduras, 
nor  have  any  Mesozoic  or  Tertiary  beds  been  discovered  in 
these  countries.  The  North  American  relationship  of  the 
relict  fauna  inhabiting  these  countries  indicates  that  they 
were  connected  by  land  with  western  Mexico.  I  shall  also 
show  later  on  that  this  region  was  united  by  land  with  western 
South  America  before  the  Isthmus  of  Panama  came  into  exis- 
tence. Possibly  the  Greater  Antilles  were  not  so  completely 
covered  by  the  sea  as  is  assumed.  They  may  have  been  repre- 
sented by  small  islands,  and  these  would  have  possessed  frag- 
ments of  an  ancient  fauna  and  flora.  Cuba,  at  any  rate, 


ANCIENT   ANTILLEAN   CONTINENT  293 

emerged  at  the  beginning  of  the  Tertiary  Era,  and  must  then 
have  been  joined  by  land  with  Mexico.  Some  time  during 
the  Oligocene  Period  Professor  Schuchert  again  records  a 
complete  submergence  of  all  the  West  Indian  islands  except 
the  Bahamas.  But  such  ancient  types  as  Typhlops,  Soleno- 
don  and  many  others,  could  not  have  been  destroyed.  We 
might  suppose  that  they  took  refuge  on  the  Bahamas,  and 
thus  repopulated  the  other  islands  subsequently.  Such  a 
theory,  however,  is  exceedingly  unlikely.  A  much  more  pro- 
bable explanation  is  that  the  Antilles  were  reduced  to  small 
islands,  and  retained  their  old  animals  and  plants.  In  early 
Miocene  times  all  the  Greater  Antilles  were  certainly  raised 
above  the  sea,  and  must  have  been  then  connected  with  one 
another.  Jamaica  was  joined  to  Guatemala,  and  Cuba  to 
Mexico,  but  Jamaica  must  have  separated  early  from  Haiti. 
While  the  islands  were  joined  to  one  another,  an  interming- 
ling of  the  more  active  ancient  types  occurred,  the  less  pro- 
gressive ones  being  forced  to  the  higher  altitudes  by  the  new 
arrivals  from  Mexico  and  Central  America.  During  the  whole 
of  Miocene  times  Yucatan  was  apparently  below  sea-level. 
When  it  rose  in  the  Pliocene  Period,  it  may  have  had  a  short 
land  connection  with  the  Antilles  by  way  of  western  Cuba. 
An  opportunity  was  then  afforded  the  mammals  of  South 
American  type  like  Amblyrhiza,  Megalocnus,  and  others  to 
spread  to  the  islands.  The  smaller  West  Indian  mammals 
came  earlier.  Central  America,  during  the  existence  of  this 
Yucatan  land  bridge,  may  still  have  been  separated  from 
North  and  South  America.  At  this  time  the  Lesser  Antilles 
probably  had  an  independent  land  connection  with  Venezuela ; 
but  that  there  was  an  Antillean  Continent  connected  with  the 
mainland  in  Pleistocene  times,  as  suggested  by  Dr.  Spencer, 
when  Central  America  had  already  been  invaded  by  the  North 
and  South  American  immigrants,  is  entirely  opposed  to  the 
results  derived  from  a  study  of  the  fauna  and  flora. 

As  for  the  trans -Atlantic  land  bridge,  we  cannot  assume 
that  it  oscillated  up  and  down  like  the  Antillean  area,  where 
peculiar  local  conditions  produced  exceptional  changes  of  land 
and  water.  Some  time  during  the  Eocene  Period  it  must 
have  enabled  European  types  to  travel  right  across  the 
Antilles  and  whatever  portions  of  Central  America  then 


294  ORIGIN   OF   LIFE   IN   AMERICA 

existed,  to  western  North  America.  I  have  endeavoured  to 
roughly  represent  on  a  map  my  conception  of  the  geographical 
conditions  then  prevailing  in  North  and  South  America 
(Fig.  14).  Then  followed  a  complete  cessation  of  the  migra- 
tory stream  to  North  America.  This  must  have  corresponded 
with  the  depression  of  the  Antilles.  During  the  Oligocene 
Period  Professor  Osborn  recorded  a  re-establishment  of  the 
faunal  resemblance  of  western  North  America  with  western 
Europe.  Here  our  correlation  of  Antillean  geology  with  that 
of  the  continental  mammalian  deposits  fails  us  completely. 
The  supposed  Oligocene  beds  of  the  Antilles  may  really  belong 
to  the  Eocene  Period.  Another  phase  of  independent  evolu- 
tion then  succeeded  this  faunal  interchange  with  western 
Europe.  This  has  been  represented  on  another  map  (Fig.  16), 
although  I  am  fully  aware  of  the  extreme  difficulties  and 
pitfalls  connected  with  such  an  attempt.  Later  on,  in 
Miocene  times,  a  fresh  invasion  occurs  from  the  Old  World. 
This,  I  think,  certainly  did  not  come  from  the  same  quarter 
as  the  others.  We  may  conclude,  therefore,  that  the  land 
bridge  between  the  Antilles  and  Europe  ceased  to  exist  some 
time  during  the  Oligocene  Period.  It  is  quite  possible  that 
long  after  that  time  large  islands  may  have  marked  the  former 
site  of  the  land  bridge,  while  temporary  land  connections  be- 
tween the  Azores  and  Europe,  and  between  the  Canary  islands 
and  Africa,  may  have  involved  certain  fragments  of  the  older 
trans-Atlantic  land  connection. 


FIG.  16. — Map  of  North  and  youth  America,  indicating  roughly  the  supposed 
conditions  of  land  and  water  about  the  middle  of  the  Tertiary  Era.  The 
ancient  land  is  slightly  tinted. 


[To  face  p.  294. 


CHAPTER  XII 

THE    GALAPAGOS    ISLANDS 

RIGHT  on  the  Equator,  off  the  west  coast  of  South  America, 
in  the  Pacific  Ocean,  lies  a  small  group  or  archipelago  of 
islands  known  as  the  "Galapagos  islands."  There  are  five 
large  islands  and  twelve  small  ones,  the  most  extensive 
(Albemarle)  being  about  eighty  miles  long  and  of  very  irre- 
gular shape,  while  the  four  next  in  importance  (Chatham, 
Indefatigable,  James  and  Narborough)  are  each  about  twenty 
or  thirty  miles  in  length,  and  of  a  rounded  or  elongate  form. 
They  are  best  seen  on  the  map  representing  the  range  of 
Helicina  (Fig.  11)  being  situated  within  the  circle  nearest 
South  America.  The  climate  of  the  islands  is  cooler  than 
that  of  any  other  equatorial  land  at  sea-level,  because  the 
temperature  of  the  surrounding  water  is  singularly  low.  This 
is  caused  by  the  Humboldt  current,  which  strikes  the  islands 
during  its  north-westerly  course  on  its  way  from  the  cold 
southern  regions.  The  lower  slopes  of  the  islands  suffer  from 
want  of  rain.  At  a  height  of  a  thousand  feet  and  upwards 
sufficient  moisture  is  condensed  to  provide  for  a  fairly 
luxuriant  vegetation. 

The  Galapagos  islands  differ  in  two  important  respects  from 
many  of  the  West  Indian  islands.  They  are  entirely  formed 
of  volcanic  rocks,  according  to  Mr.  Darwin,  who  gave  us  the 
first  reliable  description  of  them,  and  they  are  situated  at  the 
great  distance  of  seven  hundred  and  fifty  miles  from  the  main- 
land of  South  America.  The  nearest  land,  apart  from  the 
small  Cocos  islands,  is  Ecuador,  to  which  state  the  Galapagos 
archipelago  now  belongs.  In  the  case  of  the  Antilles  almost 
all  authorities  are  agreed  that  the  nucleus  of  the  fauna  re- 
presents survivals  from  the  time  when  the  islands  were  joined 
to  the  mainland,  arid  that  accidental  distribution  has  not 
greatly  modified  the  original  fauna.  In  the  Antilles  we  meet 


296  ORIGIN   OF   LIFE   IN   AMERICA 

with  a  number  of  ancient  types  of  animals  and  plants.  In  the 
Galapagos  islands  similar  relicts  of  bygone  ages  are  found,  yet 
their  presence  on  the  islands  is  not  generally  considered  to 
be  due  to  a  former  land  connection  with  the  mainland.  But 
the  question  whether  the  animals  and  plants  inhabiting  this 
archipelago  are  the  descendants  of  purely  accidental  visitors 
or  not,  is  of  more  than  usual  importance  in  this  case.  Both 
Mr.  Darwin  and  Dr.  Wallace  expressed  the  opinion  that  the 
Galapagos  islands  are  of  the  oceanic  type,  and  that  they 
originated  from  sub-oceanic  volcanoes,  having  never  formed 
part  of  a  continent  or  any  large  land-mass.  Many  of  the  more 
recent  observers  have  followed  the  lead  of  our  two  great 
naturalists.  I  need  only  mention  Professor  Agassiz,  Dr. 
Wolf,  Mr.  Salvin,  Dr.  Dall  and  Dr.  Stearns.  On  the  other 
hand,  Professor  Baur  was  the  first  to  seriously  contest  the 
view  of  these  authorities.  His  researches  led  to  a  reconsidera- 
tion of  the  problem  presented  by  the  fauna  and  flora  of  the 
Galapagos  islands  and  a  rejection  by  many  naturalists  of  the 
theory  so  ably  maintained  by  Darwin  and  his  followers. 

Islands,  as  I  have  already  indicated,  possess  many  advan- 
tages over  continental  areas  for  the  study  of  the  laws  and 
phenomena  of  distribution.  The  islands  we  are  now  dealing 
with,  moreover,  are  of  the  most  profound  importance  in  con- 
nection with  the  geological  history  of  the  two  great  American 
continents.  We  might  almost  say  that  the  problem  of  'the 
Galapagos  fauna  presents  the  key  to  the  solution  of  the  most 
complex  and  intricate  questions  concerning  the  American 
fauna  with  which  we  are  confronted.  It  is  for  this  reason 
that  the  whole  of  this  chapter  will  be  devoted  to  an  exhaustive 
survey  of  the  Galapagos  islands  and  their  inhabitants. 

When  Darwin  landed  on  the  archipelago  in  1835,  he  noted 
in  the  first  instance  the  fact  that  all  the  islands  were  formed 
of  volcanic  rock  and  that  they  contained  numerous  craters. 
The  craters  he  found  to  consist  either  of  lava  and  scoriae,  or 
of  finely-striated  sandstone-like  tuff.  All  the  latter,  which  he 
examined,  had  the  southern  sides  either  much  lower  than  the 
other  sides,  or  quite  broken  down  and  removed.  He  concluded 
from  this  fact  that  all  these  craters  were  formed  beneath  the 
sea,  and  that  their  broken  state  was  due  to  the  action  of  the 
waves  produced  by  the  southern  trade  winds.  On  the  other 


DAE  WIN   ON   GALAPAGOS   FAUNA  297 

hand,  Darwin's*  remark  that  he  noticed  a  few  fragments  of 
granite  curiously  glazed  and  altered  by  heat  among  the  ejecta- 
menta,  would  seem  to  imply  that  the  bases  of  the  craters  are 
composed  of  older  forms  of  eruptive  rocks.  This  supposition 
is  strengthened  by  an  observation  made  by  Professor  Suess,f 
that  on  the  whole  of  the  Pacific  coast  of  America  only  a  single 
mountain  range  comes  to  an  abrupt  termination  on  the  Pacific 
coast,  namely,  the  Central  American  continuation  of  the  An- 
tillean  Cordillera,  and  that  precisely  at  the  point  where  we 
might  imagine  the  arcuate  prolongation  of  this  chain  to  meet 
the  principal  Sooith  American  mountains  lie  the  volcanic, Gala- 
pagos islands.  At  any  rate,  as  Dr.  Blanford  J  has  pointed 
out,  the  rocks  of  an  island  may  be  entirely  volcanic,  although 
the  island  may  nevertheless  be  a  remnant  of  a  continental 
mass.  Except  that  some  of  the  craters  have  their  southern 
faces  broken  down,  which  may  be  due  to  some  other  cause 
than  that  suggested  by  Darwin,  the  Galapagos  islands  could 
just  as  well  represent  the  mountain  tops  of  sunken  land  as 
the  summits  of  originally  submarine  volcanoes.  Neither  of 
these  two  theories  is  supported  by  strong  geological  evidence. 
No  one  was  more  impressed  by  this  fact  than  Darwin  himself, 
and  he  bases  his  theory  of  the  origin  of  the  Galapagos  fauna 
and  flora  almost  entirely  on  the  nature,  composition  and  dis- 
tribution of  the  animals  and  plants  he  found  on  the  islands. 
His  conclusions  were  that  all  the  animals  and  plants  must  be 
derived  from  accidental  transport  by  sea-currents  or  by  birds, 
except  for  a  few  recent  immigrants  which  were  introduced  by 
man. 

The  natural  history  of  the  islands,  as  Darwin  truly  remarks, 
is  eminently  curious  and  well  deserves  attention.  Of  terres- 
trial mammals,  he  says,  there  is  only  one  which  must  be  con- 
sidered as  indigenous,  namely  a  mouse  (Mus  galapagoensis).  \ 
A.  rat  also  is  sufficiently  distinct  from  the  common  kind  to  have 
been  named  and  described,  "  but,"  continues  Mr.  Darwin, 
"  as  it  belongs  to  the  Old  World  division  of  the  family,  and  as 
this  island  had  been  frequented  by  ships  for  the  last  hundred 
and  fifty  years,  I  can  hardly  doubt  that  this  rat  is  merely  a 

*  Darwin,  C.,  "  Journal  of  Eesearches,"  pp.  270—271. 
t  Suess,  E.,  "  Das  Antlitz  der  Erde,"  II.,  p.  263. 
|  Blanford,  W.  T.,  "  Anniversary  Address,"  p.  34. 


298  ORIGIN   OF   LIFE   IN   AMERICA 

variety,  produced  by  the  new  and  peculiar  climate,  food  and 
soil  to  which  it  has  been  subjected."  Hence  Darwin  *  con- 
sidered the  rat  as  imported  by  man,  and  he  adds  that  the 
transportation  of  the  mouse  in  a  vessel  from  the  mainland 
is  not  improbable. 

Dr.  Wallace  concurs  with  Mr.  Darwin  in  the  belief  that  the 
Galapagos  islands  agree  with  all  other  oceanic  islands  in  so 
far  as  they  are  devoid  of  indigenous  mammals.  He  acknow- 
ledges that  the  mouse,  which  had  since  been  found  to  belong 
'  to  the  American  genus  Hesperomys,  differs  somewhat  from 
other  known  species.  Yet  he  remarks  that  we  can  scarcely 
consider  the  species  to  be  indigenous,  firstly  because  these 
creatures  have  been  little  studied  in  South  America,  and  that 
there  may  still  be  many  undescribed  mice  there,  and  in  the 
second  place  because  even  had  it  been  introduced  by  some 
European  or  native  vessel,  there  would  have  been  ample  time 
in  two  or  three  hundred  years  for  the  very  different  conditions 
to  have  established  a  marked  diversity  in  the  characters  of  the 
species.  Dr.  Wallace  f  reiterates  in  conclusion  Darwin's 
statement  that  the  islands  are  really  destitute  of  truly  in- 
digenous mammals. 

Now  since  these  great  naturalists  wrote  about  the  Gala- 
pagos archipelago,  and  stated  their  opinions  on  the  mam- 
malian fauna  of  the  islands,  the  latter  have  been  visited  by 
many  competent  observers,  who  brought  their  collections 
home  for  careful  study.  Thus  the  mammals  collected  by 
Dr.  Baur  on  the  islands  were  described  by  Dr.  Allen,  who 
recognised  among  them  a  typical  brown  rat  (Mus  decu- 
manus).  He  also  thought  that  a  skeleton  which  was  picked 
up  on  South  Albemarle  belonged  to  the  black  rat  (Mus  rattus). 
There  was  likewise  a  bat  which  he  identified  as  closely  allied 
to  a  Chilean  form,  but  sufficiently  distinct  to  deserve  the 
separate  name  of  Atalapha  brachyotis.  Dr.  Allen, J  moreover, 
points  out  that  the  Galapagos  mouse  does  not  belong  to  the 
Old  World  genus  "  Mus  "  nor  to  "  Hesperomys,"  but  agrees 
with  Oryzomys,  the  well-known  American  rice-rats.  Besides 


*  Darwin,  C.,  "  Journal  of  Researches,"  p.  275. 

t  Wallace,  A.  E.,  "Island  Life,"  p.  278. 

t  Allen,  J.  A.,  "  Mammals  from  the  Galapagos  Islands." 


RATS   ON   GALAPAGOS   ISLANDS  299 

Oryzomys  galapagoensis  he    found    a    second  distinct  form 
which  he  named  Oryzomys  bauri. 

A  more  important  natural  history  survey  of  the  islands 
was  made  by  the  Hopkins  Stanford  Expedition  in  1898.  In 
addition  to  the  mammals  already  known  from  the  archipelago, 
it  was  discovered  that  Narborough,  Indefatigable  and  Sey- 
mour islands  are  inhabited  by  rice-rats,  which  show  such 
structural  distinctness  in  the  interorbital  portion  of  the  skull 
that  Mr.  Heller  *  proposed  their  being  placed  into  the 
new  genus  "  Nesoryzomys."  Four  mouse-like  mammals  are 
thus  known  to  be  peculiar  to  the  Galapagos  islands,  viz., 
Oryzomys  galapagoensis;  0.  bauri,  Nesoryzomys  indefessus 
and  N.  narboroughi.  The  only  other  terrestrial  mammal  not 
found  elsewhere  is  Atalapha  or,  as  it  is  now  called, 
Lasiurus  brachyotis. 

It  is  interesting  to  note  that  the  genera  to  which  these 
species  belong  are  characteristically  American.  Both  Ory- 
zomys and  Lasiurus  have  a  wide  range  in  North  and  South 
!  America  as  well  as  in  the  Antilles.  We  have  learned  that 
Oryzomys  antillarum  is  confined  to  Jamaica.  Another  species 
lives  on  St.  Vincent,  and  several  more  on  Trinidad,  while  a 
species  (0.  nelsoni)  is  peculiar  to  the  Tres  Marias  islands  off 
the  west  coast  of  Mexico.  A  genus  ranging  from  New  Jersey 
in  the  north  to  Tierra  del  Fuego  in  South  America,  with  a 
large  number  of  species,  must  be  a  very  ancient  one;  and 
yet  not  a  single  species  occurs  outside  the  New  World. 

I  have  never  hitherto  alluded  to  bats  because  they  are  so 
generally  regarded  as  of  little  value  in  faunistic  problems. 
Specialists  of  this  group,  such  as  Dr.  Knud  Andersen,f  in- 
form us,  however,  that  this  assumption  is  by  no  means  correct, 
and  that  in  most  cases  bats  are  as  good  and  reliable  zoogeo- 
graphical  guides  as  other  small  but  non-flying  mammals. 
The  fact  that  although  Lasiurus  is  found  from  Canada  to 
Patagonia  it  has  nevertheless  preserved  its  original  habitat 
in  the  New  World,  and  has  not  even  crossed  Bering  Strait  into 
Asia,  would  seem  to  support  Dr.  Andersen's  contention,  while 
its  antiquity  is  vouched  for  by  the  occurrence  of  distinct 
species  of  Lasiurus  on  several  ^  remote  American  islands. 

*  Heller,  Edmund,  "  Mammals  of  Galapagos  Archipelago." 
t  Andersen,  K.,  "  Geogr.  Distribution  of  Khinolophus,"  p.  652. 


300  ORIGIN    OF   LIFE    IN   AMERICA 

Lasiurus  has  likewise  succeeded  in  reaching  one  other  group 
of  islands  besides  the  Galapagos  archipelago,  namely  the 
Sandwich  islands.  The  latter  are  inhabited  by  Lasiurus 
semotus,  which  is  peculiar  to  them,  and  cannot  therefore  be 
considered  as  a  recent  human  importation. 

Our  present  knowledge  of  the  mammalian  fauna  of  the 
Galapagos  islands  has  added  one  factor  of  extreme  importance 
to  those  hitherto  known,  namely  the  certainty  that  there  are 
indigenous  mammals  on  the  archipelago.  For  this  reason  the 
Galapagos  islands  should  be  excluded  from  the  oceanic 
islands,  and  be  placed  among  the  islands  which  once  formed 
part  of  a  larger  land-mass  or  continent.  It  is  not  certain, 
however,  that  Darwin  and  Wallace  would  have  taken  that  view, 
even  had  they  been  convinced  that  the  mammals  alluded  to 
were  truly  indigenous  in  the  islands.  Some  naturalists  hold 
that  even  mammals  can  be  successfully  transported  across 
the  ocean  on  tree  trunks  and  floating  islands.  Dr.  Stearns,* 
in  alluding  particularly  to  the  Galapagos  fauna,  remarks 
that  a  single  tree  of  large  size  might  carry  with  it  not  only 
molluscan  and  insect  life,  but  also  living  individuals  of  many 
vertebrate  forms  that  found  refuge  or  safety  upon  it.  Thus, 
he  continues,  if  the  environmental  conditions  were  at  all 
favourable,  colonies  of  many  animal  forms  could  be  trans- 
planted to  distant  regions.  The  possibility  of  such  an  acci- 
dental transportal  must  have  been  carefully  considered  and 
rejected  "by  Darwin  and  Wallace.  The  Humboldt  current  I 
alluded  to  as  striking  the  Galapagos  islands  does  not  come 
from  the  coast  of  Ecuador  nor  from  Central  America.  It 
originates  in  the  far  south,  and,  passing  northward,  skirts  the 
coast  of  Chile  and  southern  Peru,  and  then  leaves  the  land  in  a 
north-westward  direction.  The  tree  trunks  spoken  of  by  Dr. 
Stearns  as  carriers  of  all  kinds  of  animal  life  would  have  had 
to  travel  several  thousand  miles,  no  doubt  experiencing  stormy 
weather  on  the  way,  before  they  could  have  safely  deposited 
their  loads  of  vertebrates  on  the  shores  of  the  Galapagos 
islands.  If  these  floating  trees  are  responsible  for  the  present 
mammalian  fauna  of  these  islands,  how  is  it  that  they  have 
brought  nothing  new  to  them  since  their  occupation  by  man  ? 

*  Stearns,  E.  E.  0.,  "  Mollusk-fauna  of  the  Galapagos  Islands,"  p.  366. 


ACCIDENTAL   DISPERSAL  301 

Man  has  brought  the  brown  and  the  black  rats  apparently. 
Why  should  the  agencies  of  accidental  transport  have  been 
so  much  more  potent  in  the  distant  past  than  they  are 
now  ?  We  might  add  also,  is  it  possible  that  these  same 
agencies  should  be  able  to  select  the  most  ancient  forms  of 
life  as  more  suitable  for  transport  than  more  modern  pro- 
ductions ?  Of  course,  these  ideas  of  mammals  being  carried 
across  a  vast  expanse  of  ocean  and  safely  landed  on  a  distant 
shore  are  mere  conjectures  unsupported  by  any  evidence. 

"  Of  land-birds,"  says  Mr.  Darwin,  "  I  obtained  twenty-six 
kinds,  all  peculiar  to  the  archipelago  and  found  nowhere  else, 
with  the  exception  of  one  lark -like  finch  (Dolichonyx  oryzi- 
vorus)  from  North  America."  Of  waders  and  water-birds  he 
succeeded  in  capturing  eleven  kinds,  only  three  of  them  being 
new  species.  In  1875  the  number  of  land-birds  known  to  Mr. 
Salvin  had  increased  from  twenty-five  to  thirty-six  species. 
Most  of  the  genera  to  which  they  belong  are  of  very  wide 
distribution ;  seven,  however,  are  confined  to  continental 
America,  leaving  five  peculiar  to  the  islands.  Mr.  Salvin  * 
expresses  no  doubts  as  to  the  correctness  of  Darwin's  inter- 
pretation of  the  origin  of  the  Galapagos  islands.  Hence  he 
concludes  that  the  birds  now  found  on  the  islands,  being 
related  to  American  birds,  must  have  emigrated  from'  America 
and  have  become  modified  by  the  different  climatic  condi- 
tions with  which  they  were  surrounded.  A  later  review  of  the 
Galapagos  birds  was  undertaken  by  Mr.  Bidgway  f  in  1897, 
when  the  number  of  land-birds  recorded  from  the  islands  was 
nearly  doubled.  He  notes  the  exact  distribution  of  the  various 
species  and  varieties  in  detail,  and  shows  how  circumscribed 
their  range  is.  Of  the  five  genera  peculiar  to  the  islands 
only  two,  viz.,  Nesomimus  and  Nesopelia  are  of  evidently 
American  relationship.  The  remaining  three,  he  thinks,  have 
so  obvious  a  leaning  towards  certain  Hawaiian  dicaeidine 
forms,  that  the  possibility  of  a  former  land  connection  with 
the  Sandwich  islands,  either  continuous,  or  by  means  of  inter- 
mediate islands  as  "  stepping  stones,"  becomes  a  factor  in 
the  problem  of  their  origin.  "It  may  be,"  he  adds,  "that 
the  resemblance  of  Cocornis,  Cactornis  and  Camarhynchus 

*  Salvin,  0.,  "  Avifauna  of  Galapagos  Archipelago." 

t  Eidgway,  E.,  "  Birds  of  Galapagos  Archipelago,"  p.  467. 


302  ORIGIN   OF   LIFE    IN   AMERICA 

to  the  above-mentioned  Hawaiian  forms,  is  merely  a  super- 
ficial one,  and  not  indicative  of  real  relationship.  Drs.  Roth- 
schild and  Hartert,  indeed,  believe  that  this  is  the  case,  but 
as  a  certain  affinity  between  these  widely  separated  islands 
undoubtedly  exists  in  some  other  groups,  Mr.  Ridgway's  view 
may  possibly  turn  out  to  be  the  correct  one.  Moreover,  as 
Mr.  Ridgway  points  out,  two  of  the  Hawaiian  Procellariidae, 
viz.,  Aestrelata  phaeopygia  and  Oceanodroma  cryptoleucura 
occur  in  the  Galapagos  islands. 

Drs.  Rothschild  and  Hartert  *  derive  the  whole  avifauna 
from  America.  All  the  same,  their  studies  do  not  lead  them  to 
adopt  Darwin's  theory.  They  remain  uncertain  whether  the 
fauna  points  to  a  former  land  connection  with  the  mainland 
or  whether  it  owes  its  existence  to  accidental  dispersal.  That 
there  should  be  this  doubt  in  their  minds  is  rather  surprising, 
considering  their  own  statement  that  the  geological  evidence 
is  entirely  opposed  to  the  theory  of  a  former  land  bridge  be- 
tween the  islands  and  America. 

The  most  recent  study  on  the  birds  of  the  Galapagos  archi- 
pelago is  that  of  Messrs.  Snodgrass  and  Heller,  f  Taking 
the  general  results  of  all  these  papers,  there  can  be  no 
doubt  that  the  avifauna  is  mostly  related  to  South  and  Central 
America  and  the  West  Indies,  thus  agreeing  in  that  respect 
with  the  mammalian  fauna. 

The  reptiles  of  the  Galapagos  islands  certainly  offer  the 
greatest  difficulty  to  the  acceptance  of  Darwin's  theory  that 
the  islands  have  risen  from  the  floor  of  the  ocean  and  have 
never  been  connected  with  one  another  or  with  the  continent. 
Darwin  observed  only  one  small  lizard  belonging  to  a  South 
American  genus,  two  different  kinds  of  the  great  lizard 
Amblyrhynchus — a  genus  confined  to  the  islands — one  kind 
of  snake  and  a  land  tortoise.  He  noticed  that  the  one  kind  of 
Amblyrhynchus  lived  altogether  on  land,  the  other  being 
semi-aquatic.  The  latter  he  described  as  a  hideous  looking 
black  creature  up  to  four  feet  in  length,  with  a  laterally 
flattened  tail  and  webbed  feet.  Sluggish  in  their  movements 
on  shore  these  huge  lizards  are  expert  swimmers,  darting 

*  Rothschild,  W.,  and  E.  Hartert,   "  Ornithology  of  the  Galapagos 
Islands,"  pp.  137—139. 

t  Snodgrass,  E.  E.,  and  E.  Heller,  "Birds  of  the  Galapagos  Islands." 


BIKDS   OF   GALAPAGOS   ISLANDS  303 

among  the  rock -pools  and  feeding  there  on  seaweed.  The 
terrestrial  species  has  no  webs  on  the  toes,  and  is  of  about  the 
same  size  as  its  aquatic  relative,  reddish  brown  above  and 
yellow  underneath.  It  inhabits  burrows,  which  occur  in  such 
numbers  that  the  soil  is  constantly  giving  way  as  one  walks 
over  them,  much  to  the  annoyance  of  the  tired  traveller,  as 
Mr.  Darwin  *  remarks.  Some  of  the  tortoises,  according  to 
Darwin,  grow  to  an  immense  size,  yielding  as  much  as  two 
hundred  pounds  of  meat.  Like  the  two  lizards  they  are 
entirely  vegetable  feeders. 

When  Dr.  Gunther  f  described  the  reptilian  fauna  of  the 
islands  he  distinguished  five  species  of  lizards  instead  of 
the  three  mentioned  by  Darwin.  The  gigantic  tortoises, 
moreover,  he  thought,  were  referable  to  five  distinct  forms, 
every  one  of  them  inhabiting  a  different  island.  He  did  not 
speculate  on  their  origin  or  past  history,  but  mentioned  that, 
although  large  land-tortoises  are  now  restricted  to  the  two 
widely  separated  regions  of  the  Galapagos  islands  on  the 
one  hand,  and  the  Mascarenes  and  Seychelles  on  the  other, 
they  formerly  had  an  extensive  range.  In  the  Miocene  Period 
they  lived  in  India,  southern  Europe  and  in  North  and  South 
America.  We  may  consequently  look  upon  the  few  survivors 
as  relicts  of  Tertiary  times.  J 

More  recent  researches  on  the  reptiles  show  that  there  are 
far  more  distinct  forms  than  was  anticipated  even  by  Dr. 
Gunther.  Mr.  Garman§  alludes  to  twenty-two  species,  among 
them  several  geckos.  He  does  not  enter  into  a  discussion  as 
to  their  origin ;  he  merely  states  that  two  theories  have  been 
advanced  to  explain  the  affinities  of  the  fauna. 

The  Hopkins- Stanford  Expedition  of  1898  made  such  ex- 
tensive collections  on  the  islands  that  many  additional  forms 
were  discovered  among  the  material  sent  to  the  Museum  of  the 
Stanford  University.  Mr.  Heller,  who  describes  the  reptiles, 
mentions  twenty-five  species  and  several  varieties.  Nine  of 
these  are  giant  tortoises,  fifteen  are  lizards,  and  there  is  one 
snake.  Among  the  lizards  there  are  six  geckos  (Geckonidae) 

*  Darwin,  C.,  "  Journal  of  Eesearches,"  pp.  278—284. 

t  Gunther,  A.,  "  Zoological  Collections  from  Galapagos,"  p.  66. 

t  Gunther,  A.,  "  Gigantic  Land-tortoises,"  p.  253. 

§   Garman,  S.,  "  Eeptiles  of  Galapagos  Islands." 


304  ORIGIN   OF   LIFE   IN   AMERICA 

belonging  to  the  two  genera  Gonatodes  and  Phyllodactylus. 
The  single  species  of  Gonatodes  is  most  closely  allied  to  a 
species  found  in  the  West  Indies,  while  the  genus  also  occurs 
along  the  coast  of  Ecuador  and  Peru.  Of  the  five  species 
of  Phyllodactylus,  four  are  peculiar  to  the  Galapagos  archi- 
pelago and  more  or  less  nearly  related  to  P.  tuberculosus,  the 
non-peculiar  species  being  distributed  along  the  west  coast 
of  Mexico,  Central  and  South  America  as  far  as  Ecuador. 
All  the  species  of  Tropidurus,  a  genus  belonging  to  the  family 
Iguanidae,  are  peculiar  and  closely  related  forms,  most  of 
them  being  confined  to  different  islands.  The  genus  is  prin- 
cipally found  in  Peru  and  Ecuador.  The  two  very  large  lizards 
which  Darwin  observed  really  belong  to  distinct  genera.  Two 
species  of  Conolophus  are  now  recognised,  while  the  aquatic 
form  still  retains  the  original  name  of  Amblyrhynchus  cris- 
tatus.  ,  Both  genera  of  Iguanidae  are  quite  peculiar  to  the 
archipelago  and  distantly  related  to  a  South  American  genus. 
Finally,  the  snake  Dromicus  biserialis,  which  is  met  with  on 
seven  of  the  islands,  is  nearly  akin  to  D.  chamissonis  of  Chile 
and  Peru. 

The  reptiles  thus  exhibit  affinity  with  those  inhabiting 
western  South  America,  Central  America  and  the  West  Indies. 
If  they  had  reached  the  Galapagos  islands  by  means  of  marine 
currents,  as  has  been  alleged,  one  may  be  tempted  to  ask  the 
same  question  as  I  put  before — Why  should  practically  all  the 
species  belong  to  ancient  types  ?  Giant  tortoises  seem  to  have 
become  extinct  on  the  continents  in  Miocene  times,  while  the 
lizards  of  the  archipelago  belong  to  the  two  families  Gecko  - 
nidae  and  Iguanidae.  Although  no  fossil  representatives  of  the 
Geckonidae  are  known,  the  resemblance  of  their  vertebrae  to 
those  of  the  Palaeozoic  Microsauri  has  been  commented  upon 
as  indicating  their  ancient  lineage.  The  genus  Phyllodactylus 
occurs  in  tropical  America,  in  Africa,  Madagascar,  Australia 
and  on  Norfolk  and  Lord  Howe's  islands  in  the  Pacific.  A 
single  species  inhabits  the  western  Mediterranean  region.  The 
distribution  of  the  genus,  therefore,  is  suggestive  of  a  very 
remote  origin.  Of  the  Iguanidae,  as  I  have  already  pointed 
out,  (p.  127),  we  know  that  they  lived  in  America  in  Creta- 
ceous, and  in  Europe  in  Eocene  times,  while  at  present  they 
are  confined  to  North  and  South  America  with  the  outlying 


GALAPAGOS   TOETOISES  305 

Tres  Marias,  Galapagos  and  Chiloe  islands.  Beyond  this 
centre  of  distribution  there  are  only  two  remote  stations,  one 
in  Madagascar,  the  other  on  the  Fiji  islands.  We  could  not 
have  a  better  example  of  discontinuous  distribution,  which, 
as  Dr.  Wallace  has  always  urged,  is  a  proof  of  antiquity. 
Lastly,  the  Galapagos  snake  belongs  to  the  ancient  family 
Colubridae,  which  also  includes  Tropidonotus,  a  genus 
specially  alluded  to  (pp.  128  and  222). 

In  spite  of  these  facts,  Mr.  Heller  *  expresses  the  opinion 
that  the  archipelago  is  mostly  of  Tertiary  age,  and  that  the 
fauna  has  been  chiefly  derived  from  material  carried  by  ocean 
currents. 

Still  another  expedition  has  lately  been  sent  to  the  archi- 
pelago by  the  California  Academy  of  Sciences.  Dr.  Van 
Denburghf  who  was  asked  to  report  on  the  reptiles  feels  quite 
convinced  that  the  islands  must  all  at  some  former  period 
have  formed  parts  of  a  single  land-mass.  In  a  letter  which  he 
addressed  to  me,  he  implies  that  several  species  of  snakes 
inhabit  the  islands.  He  states  that  "the  closest  relatives 
of  the  serpents  of  the  Galapagos  archipelago  are  native  to  the 
Bahamas,  Greater  and  Lesser  Antilles,  Costa  Eica  and  the 
whole  of  South  America.  This  being  true,  the  snakes  of  these 
localities  must  have  had  a  common  origin.  Either  the  West 
Indian  and  Galapagos  snakes  have  been  derived  from  South 
America,  or  else  all  must  be  descendants  of  species  occupy- 
ing a  great  central  land-mass  which  has  sunk  below  the  level 
of  the  sea,  leaving  mere  remnants  in  Central  America, 
northern  South  America,  the  Antilles  and  the  Galapagos. 
Either  view  implies  a  former  land  connection  and  a  con- 
tinental origin  of  the  Galapagos  ophidian  fauna.  1  cannot 
bring  myself  to  share  the  opinion  of  those  who  believe  that 
the  fauna  of  the  Galapagos  has  reached  these  islands  by  the 
more  or  less  accidental  agency  of  the  winds  and  ocean 
currents." 

When  Dr.  Stearns  J  reported  upon  the  land  and  fresh-water 
snails  inhabiting  the  Galapagos  archipelago,  he  alluded  to  one 

*  Heller,  E.,  "  Hopkins-Stanford  Expedition  :  Keptiles,"  pp.  46— 48. 
t  Denburgh,  John  Van,  "  Preliminary  Descriptions  of  Land-tortoises," 
p.  1. 

I  Stearns,  E.  E.  C.,  "  Mollusk-fauna  of  the  Galapagos,"  pp.  359—370. 
L.A.  X 


306  ORIGIN  OF   LIFE   IN  AMERICA 

species  of  Hyalinia,  a  large  number  of  Bulimuli,  two  Pupae, 
one  Leptinaria,  a  Succinea  and  a  Helicina  as  having  been 
collected  on  the  islands  by  previous  visitors.  He  then  dilates 
upon  the  various  accidental  means  of  transport,  and  concludes 
that  the  agency  of  winds  and  ocean  currents  is  amply  sufficient 
to  explain  the  origin  of  the  molluscan  fauna.  He  acknow- 
ledges that  the  archipelago  is  situated  within  an  almost  wind- 
less area,  where  storms  are  of  rare  occurrence,  yet  maintains 
that  during  the  course  of  ages  the  climatic  features  may  have 
been  different  from  those  obtaining  at  present.  He  also 
emphasises  the  fact  of  the  tenacity  of  life  of  mollusks  and 
the  length  of  time  they  are  able  to  subsist  without  food,  claim- 
ing that  a  theory  which  will  fairly  explain  a  good  portion  of 
the  phenomena  of  distribution  by  such  agencies  and  operating 
directly  under  our  eyes,  is  preferable  to  those,  however  plau- 
sible and  attractive,  involving  conjectural  and  remoter  con- 
ditions. 

In  his  endeavour  to  support  the  theory  of  accidental  dis- 
tribution as  applied  to  the  origin  of  the  Galapagos  fauna,  Dr. 
Stearns  seems  to  forget  that  no  observation  has  ever  been 
made  clearly  indicating  the  conveyance  of  mollusks  or  their 
eggs  in  drift-timber.  Mollusks  have  never  been  found 
in  the  crevices  or  under  the  bark  either  of  trees  encountered 
on  the  sea  or  of  those  stranded  on  foreign  coasts.  Very 
shortly  after  the  trees  are  stranded,  they  are  no  doubt  invaded 
by  all  sorts  of  creatures  seeking  moisture  and  shelter ;  but  the 
theory  of  accidental  distribution,  so  ably  advocated  by  many 
eminent  naturalists  still  involves  a  good  deal  of  the  conjecture 
which  Dr.  Stearns  is  so  anxious  to  avoid.  Although  Dr. 
Ball  *  fully  acknowledges  that  we  possess  no  actual  proof 
in  support  of  the  drift-theory,  he  also  concurs  with  Dr. 
Stearns  in  the  opinion  that  there  can  be  little  doubt  of  the 
land  snails  having  been  introduced  to  the  Galapagos  islands 
in  that  manner.  In  his  review  of  the  molluscan  fauna  of  the 
islands,  he  mentions  thirty-three  species  of  Bulimuli,  two 
species  of  Vitrea  and  one  of  Conulus,  two  Pupae,  four 
Succineae,  one  Tornatellina  (Leptinaria),  one  Helicina  and 
finally  one  Endodonta.  Of  these  forty-five  species,  only  a 

*  Dall,  W.  H.,  "Insular  Land-shell  Faunas." 


GALAPAGOS  MOLLUSKS  307 

couple  are  probably  common  to  the  islands  and  the  main- 
land. All  the  others  are  restricted  and  quite  peculiar  to  the 
Galapagos  archipelago.* 

The  genus  Bulimulus,  to  which  most  of  the  Galapagos  snails 
belong,  comprises  mostly  species  with  ovate  large  heavy  shells, 
which  would  seem  to  be  peculiarly  unfit  for  accidental  trans- 
port by  marine  currents,  though  many  live  almost  habitually 
on  shrubs.  As  defined  by  Dr.  Pilsbry,  the  genus  is  restricted, 
as  I  have  already  indicated,  to  the  western  borders  of  South 
and  Central  America  and  beyond  the  latter  as  far  north  as 
Mexico  and  Lower  California.  Eastward  it  passes  along  the 
northern  States  of  South  America  to  Brazil,  it  extends  to  the 
Antilles,  and  from  Mexico  to  the  southern  United  States. 
Thus  it  is  limited  to  North,  South  and  Central  America,  the 
West  Indies  and  Galapagos  islands.  The  Melanesian  genera 
Liparus  and  Placostylus  are  closely  related.  The  range  of  the 
large  family  Bulimulidae  is  very  similar,  one  group  being  con- 
fined to  America,  the  other  to  the  opposite  side  of  the  Pacific, 
from  Tasmania  in  the  south  through  Australia  to  China  north- 
ward, and  eastward  to  the  Society  islands.  One  is  almost 
tempted  to  invoke  a  Pacific  continent  in  explanation  of  this 
curious  discontinuous  distribution.  It  seems  as  if  the  family 
had  originated  in  some  central  Pacific  area  and  had  taken 
refuge  on  the  nearest  lands  east  and  west  on  the  disappear- 
ance of  its  ancient  habitat.  But  we  need  not  consider  this 
problem  at  present. 

There  are  three  groups  of  apparently  very  closely  related 
Bulimuli  in  Chile  and  Peru,  in  the  Galapagos  islands  and  in 
Lower  California.  The  shelLin  these  groups  certainly  is  very 
similar,  being  narrow  and  elongated,  and  possessing  the  same 
texture.  All  the  same,  Dr.  Pilsbry  f  is  of  opinion  that  this 
similarity  in  appearance  is  not  to  be  looked  upon  as  indicating 
close  relationship,  but  as  a  case  of  convergence  produced  by 
similar  environments.  He  recognises  three  sections  of  Buli- 
mulus according  to  the  sculpture  of  the  apical  whorls  of  the 
shell.  The  first  of  these  lives  in  Argentina,  Chile,  Peru  and 
Bolivia,  the  second  in  tropical  America,  the  Galapagos  islands 

*  Ball,  W.  H.,  "  Insular  Land-shell  Faunas  :  Additions." 
t  Pilsbry,  H.  A.,  "Manual  of  Conchology,"  (Pulmonata),  X.,  p.  127. 

x2 


308  ORIGIN   OF   LIFE   IN   AMERICA 

and   West   Indies,   the    third    in    Mexico    and    the    United 
States. 

The  two  species  of  Vitrea  (Hyalinia)  seem  to  b©  related  to 
the  Vitrea  radiatula  group,  which,  like  Conulus,  has  a  very 
wide  range  in  the  Old  World  and-  the  New.  One  of  the  Gala- 
pagos species  of  Pupa  is  apparently  found  in  Ecuador  also, 
the  other  is  peculiar  to  the  islands.  The  genus  has  a  world- 
wide range.  All  the  species  of  Succinea,  a  genus  which  has 
an  enormous  range,  are  confined  to  the  islands.  Tornatellina 
chathamensis  is  closely  related  to  the  Hawaiian  Achatellina 
and  belongs  to  a  typically  Polynesian  genus.  Helicina,  as 
already  pointed  out  (pp.  157 — 158),  has  evidently  invaded 
America  from  the  Pacific.  Considering  that  it  is  an  operculate 
shell,  and  therefore  supposed  to  be  specially  fitted  for  trans- 
port across  the  sea  by  marine  currents,  it  is  surprising  that 
only  a  single  species  of  Helicina  should  have  taken  advantage 
of  these  facilities  (^compare  Fig.  11).  Lastly,  one  species  of 
Endodonta  (E.  helleri)  has  been  observed  on  the  archipelago. 
Of  the  Galapagos  mollusks  this  is  one  of  the  most  in- 
teresting, because  the  extremely  primitive  genus  Endodonta 
is  almost  confined  to  the  Pacific  region,  including  New  Zea- 
land, Tasmania,  Australia,  New  Guinea  and  the  Philippine 
islands.  Only  St.  Helena,  where  it  is  also  found,  lies  entirely 
outside  the  area.  It  is  significant  that  not  a  single  species  is 
known  from  the  American  or  Asiatic:  mainlands  or  the  West 
Indies. 

I  cannot  help  thinking  that  the  attempt  to  derive  the  Gala- 
pagos molluscan  fauna  from  America  is  a  mistake.  The 
family  Bulimulidae  is  Pacific  in  origin,  rather  than  American. 
Succinea  and  Pupa  have  a  wide  range  in  the  Pacific  islands, 
Tornatellina  and  Endodonta  are  altogether  Pacific,  being  un- 
known in  America,  Helicina  is  mainly  Pacific,  and  it  has 
entered  America  from  the  west.  Only  Vitrea  and  Conulus  may 
be  looked  upon  as  typically  American  and  Old  World  genera  of 
great  antiquity.  With  their  exception  all  the  other  genera 
except  two  are  more  likely  to  have  passed  into  America  from 
the  direction  of  the  Galapagos  islands  than  vice  versa.  The 
two  others  stopped  short  at  the  Galapagos  archipelago  and 
went  no  further  east. 

Too  little  is  as  yet  known  of  the  insects  of  the  islands  and 


AFFINITIES   OF   GALAPAGOS   SNAILS         809 

their  distribution  to  be  of  much  service  in  this  study,  but 
Dr.  Giinther  records  a  woodlouse  (Cubaris  galapagoensis), 
which  is  apparently  related  to  a  West  Indian  form.  The  genus 
Cubaris,  which  is  otherwise  confined  to  the  West  Indies, 
Florida,  Central  America,  California  and  South  America,  is 
the  American  representative  of  Armadillo.  The  latter  has  its 
headquarters  in  southern  Europe.  Cubaris,  no  doubt,  owes'its 
presence  in  America  to  the  fact  that  some  ancestor  common 
to  it  and  the  European  ^Armadillo  crossed  over  by  the  trans- 
Atlantic  land  bridge  described  in  the  last  chapter. 

On  the  whole,  remarks  Dr.  Wallace,*  the  flora  agrees  with 
the  fauna  as  indicating  a  moderately  remote  origin,  great 
isolation,  and  changes  of  conditions  affording  facilities  for 
the  introduction  of  organisms  from  various  parts  of  the 
American  coast,  and  even  from  the  West  Indian  islands  and 
the  Gulf  of  Mexico.  As  in  the  case  of  the  birds,  he  continues, 
the  several  islands  differ  considerably  in  their  native  plants, 
many  species  being  limited  to  one  or  two  islands  only,  while 
others  extend  to  several. 

A  point  of  great  importance  in  connection  with  the  theory 
of  dispersal  of  seeds  by  marine  currents  is  the  condition  of 
the  coasts  of  the  Galapagos  islands.  The  dried  up  desert 
aspect  of  the  islands  on  landing  has  been  commented  upon  by 
Darwin.  Dr.  Wolff  gives  us  his  impression  of  the  same 
islands  during  the  rainy  season.  The  lower  zone  up  to  six 
hundred  feet  is  only  very  sparsely  covered  by  vegetation.  The 
whole  landscape  has  a  greyish-brown  appearance.  A  .Lantana, 
a  couple  of  Crotons  and  a  few  Euphorbiaceae  and  Compositae 
are  the  principal  members  of  this  wretched  flora.  The  only 
plants  that  thrive  in  this  district  are  two  giant  Cactuses, 
reaching  to  a  height  of  about  twenty  feet.  They  seem  to 
select  the  driest  and  roughest  spots,  where  nothing  else  will 
grow.  Herbaceous  plants  are  restricted  in  this  lower  zone 
to  a  few  parched  grasses  and  a  few  shrivelled  diminutive 
plants.  There  are  very  large  districts,  moreover,  where 
nothing  whatsoever  will  grow,  the  ground  being  paved,  as  it 
were,  with  enormous  blocks  of  lava.  At  a  height  of  about 

*  Wallace,  A.  E.,  "  Island  Life,"  p.  289. 

f  Wolf,  Th.,  "  Die  Galapagos  Inseln,"  pp.  257—260. 


310  ORIGIN   OF   LIFE   IN   AMERICA 

seven  hundred  feet  the  scenery  changes  completely.  A  fresh 
and  moisture-laden  wind  greets  us  from  the  south-east,  the 
ground  is  covered  with  short  dense  grasses,  evergreen,  shady 
little  woods  are  dotted  about  here  and  there,  and  the  flora 
as  a  whole  is  quite  different  from  that  below.  Those  ac- 
quainted with  the  flora  of  Ecuador  will  feel  as  if  transplanted 
to  the  woods  of  the  Paramo  region,  which  flourish  at  a  height 
of  about  9,000  feet.  The  most  striking  character  of  the 
flora  is  its  strong  endemism,  every  one  of  the  larger  islands 
having  its  peculiar  species,  which  do  not  range  to  the 
others  even  when  the  islands  are  in  close  proximity  to  one 
another. 

From  Dr.  Wolf's  graphic  description  we  can  gather  valu- 
able information.  In  its  strongly  endemic  character  the  flora 
of  the  archipelago  agrees  perfectly  with  the  fauna.  As  among 
the  animals  so  it  has  been  noticed  among  the  plants  that  the 
various  islands  all  possess  their  own  species,  though  the  latter 
are  related  to  one  another.  But,  in  answer  to  our  inquiries 
into  the  causes  of  this  singular  distribution,  we  are  told  by 
Dr.  Wolf  that  he  concurs  with  Darwin  in  the  belief  that  the 
islands  received  their  plants,  as  well  as  their  animals,  by  acci- 
dental means  of  transport.  He  does  not  specify  these  means 
of  transport.  Darwin*  makes  it  perfectly  clear  to  us  that 
winds  could  not  have  played  any  part  in  it.  "  As  the  archi- 
pelago is  free  to  a  remarkable  degree,"  he  says,  "from  gales 
of  wind,  neither  the  birds,  insects,  nor  lighter  seeds,  would 
be  blown  from  island  to  island."  If  the  seeds  were  carried 
by  marine  currents  from  the  mainland  to  the  archipelago, 
how  were  they  afterwards  conveyed  from  the  inhospitable 
shores  of  the  islands  across  the  almost  absolute  desert  of 
the  lowlands  to  the  higher  level  ?  We  are  unacquainted  with 
any  forces  except  wind,  which  would  carry  the  seeds  to  a 
height  of  seven  hundred  feet,  but  Darwin  expressly  tells  us 
the  islands  are  remarkably  free  from  wind.  Moreover,  we 
should  expect  the  plants  found  at  that  height  in  the  Galapagos 
islands  to  agree  to  some  extent  with  the  flora  of  the  lowlands 
of  the  continent.  Few,  if  any,  seeds  carried  down  by  rivers 
would  come  from  the  highlands  of  the  Andes.  Yet  the  Gala- 

*  Darwin,  C.,  "Journal  of  Researches,"  p.  290. 


FLOKA   OF   GALAPAGOS  ISLANDS  311 

pagos  flora  possesses  affinities  with  the  highlands  rather  than 
the  lowlands. 

In  this  brief  account  of  the  main  features  of  the  fauna  and 
flora  of  the  Galapagos  archipelago  I  have  endeavoured  to  state 
mainly  the  opinions  of  those  who  agree  with  the  theory  of 
elevation  a,s  propounded  by  Darwin.  Some  authorities  formu- 
lated no  decisive  views  on  the  subject.  It  is  currently  believed 
that  the  first  criticism  of  this  theory  was  brought  forward  by 
Professor  Baur  *  in  1890,  in  a  paper  on  the  variation  of  the 
genus  Tropidurus  in  the  Galapagos  islands.  Although  it  was 
the  first  serious  criticism,  Mr.  Andrew  Murray  f  remarked 
much  earlier  that  Darwin's  observations  on  the  Galapagos 
fauna  had  led  him  to  an  entirely  different  conclusion.  "  The 
American  type  of  the  whole  group,"  he  says,  "  speaks  pri- 
marily of  connection  with  the  continent.  The  family  facies 
of  the  group  inter  ,se,  speaks  of  a  period  when  the  whole 
islands  were  separated  from  America,  but  united  to  each  other. 
The  endemic  peculiarity  of  the  species  of  each  individual 
island  tells  of  subsequent  separation  and  change  wrought 
in  each,  probably  at  the  same  time,  by  the  alteration  of  climate 
from  continental  or  terrestrial,  to  isolated  and  oceanic." 

It  was  not  until  1891,  when  a  more  popular  account  of 
Professor  Baur's  views  appeared  in  the  "  American  Natu- 
ralist," that  his  opinions  led  to  considerable  discussion  both 
in  America  and  in  Europe.  It  had  seemed  as  if  Darwin's 
theory,  supported  as  it  was  by  Wallace,  Hooker,  Agassiz  and 
many  other  naturalists  of  less  note,  was  unassailable.  Never- 
theless, Professor  Baur's  careful  reasoning  induced  many  sub- 
sequent writers  to  ad/>pt  his  views  in  preference  to  older 
ones.  He  urged  with  Dr.  Wallace  that  all  islands  may  be 
divided  into  Continental  and  Oceanic  ones.  The  first  have 
developed  from  continents  or  larger  bodies  of  land  through 
isolation  or  subsidence.  The  second  have  not  been  so  formed, 
but  have  arisen  from  submarine  portions  of  the  earth  by  eleva- 
tion. He  thought  that  the  fauna  and  flora  of  the  first  group  of 
islands  would  be  more  or  less  harmonic,  that  is  to  say,  the 
islands  would  be  like  satellites  of  the  continent  from  which 
they  took  their  origin.  The  fauna  and  flora  of  the  second 

*  Baur,  G.,  "  Variieren  der  Eidechsen-Ofattung  Tropidurus." 
t  Murray,  A.,  "  Distribution  of  Mammals,"  p.  17. 


312  ORIGIN   OF   LIFE   IN  AMERICA 

group,  however,  ought  to  be  disharmonic,  for  it  will  be  com- 
posed of  quite  a  different  mixture  of  animals  and  plants,  since 
they  have  been  introduced  accidentally  from  other  land  areas. 
Accidental  immigrants  will  also  reach  the  continental  islands 
eventually  in  a  similar  manner.  Thus  continental  islands 
may  be  composed  of  two  f  aunal  and  floral  elements,  an  original 
and  a  secondary  one.  Oceanic  islands,  on  the  other  hand,  can 
only  contain  a  secondary  faunal  and  floral  element,  and  will, 
therefore,  not  exhibit  harmonic  distribution.  Since  the  dis- 
tribution of  the  animals  and  plants  on  the  Galapagos  islands 
is  harmonic,  just  as  it  is  on  the  West  Indian  islands,  both  of 
them,  according  to  Professor  Baur,  represent  the  remains 
of  land-masses  that  have  been  split  off  from  the  adjoining 
continent,  and  they  have  not  risen  from  the  floor  of  the 
ocean.  Though  agreeing  in  his  final  conclusions  with  Pro- 
fessor Baur,  I  am  unable  to  follow  him  in  regard  to  his  defini- 
tions of  "  harmonic  "  and  "  disharmonic."  Some  of  the 
Pacific  islands  are  looked  upon  by  Professor  Baur  himself  as 
remnants  of  a  Pacific  continent,  others,  I  believe,  are  not. 
Where  is  the  exact  distinction  between  them  in  the  nature  of 
their  fauna  ? 

A  few  years  later  Professor  Baur  *  once  more  returned  to 
the  subject  in  order  to  answer  the  objections  brought  against 
his  theory  by  numerous  critics.  He  also  intended  to  make  some 
remarks  on  the  geological  history  of  the  Pacific  Ocean,  and 
from  his  preliminary  observations  it  is  evident  he  believed 
in  its  comparatively  recent  age ;  but  before  he  could  complete 
his  interesting  series  of  articles  his  sudden  death  unfortu- 
nately deprived  us  of  further  communications.  From  his 
writings,  however,  we  know  that  Professor  Baur  believed  that 
the  Galapagos  archipelago  represented  the  remnants  of  a  large 
peninsula  which  joined  the  West  Indies  by  way  of  Cocos 
island  and  Central  America.  As  some  of  his  critics  maintain 
that  in  his  views  Professor  Baur  stands  almost  alone,  and  is 
opposed  by  most  of  those  who  have  discussed  the  fascinating 
problem  of  the  origin  of  the  Galapagos  archipelago,  a  few 
remarks  may  be  permissible  in  support  of  this  theory. 

Alluding  to  the  gigantic  land-tortoises  which  have  survived 

*  Baur,  G.,  "New  Observations  on  the  Galapagos  Islands." 


BAUK'S   CEITICISMS  313 

on  the  Galapagos  and  various  other  islands,  Dr.  Gadow  *  asks 
the  pertinent  question — Where  did  all  these  creatures  come 
from,  and  how  did  they  get  to  these  oceanic  islands  ?  Acci- 
dental transport  is  out  of  the  question,  as  land-tortoises  are 
drowned  within  a  few  hours  after  immersion  in  water.  Since 
none  of  their  kind  inhabit  the  great  continents  now,  although 
they  lived  there  formerly,  we  are  constrained  to  assume  that 
the  existing  species  are  the  survivors  of  tortoises  which  pro- 
ceeded to  the  islands  when  they  were  connected  by  land  with 
the  adjoining  continents.  In  another  place  Dr.  Gadow  quotes 
the  Galapagos  tortoises  as  supporting  the  hypothesis  of  an 
Oligocene  extension  of  land,  considerably  to  the  west  and 
south  of  the  present  Central  America.  In  his  maps  illus- 
trating the  palaeogeography  of  Middle  America,  he  actually 
joins  the  Galapagos  islands  with  the  Antilles,  as  Professor 
Baur  had  done,  by  way  of  Cocos  island. f 

Professor  Boettger  J  approves  of  the  results  obtained  by 
Professor  Baur's  methods  of  investigation,  arguing  that  the 
facts  of  distribution  are  much  more  easily  explained  by  the 
assumption  of  a  former  land  connection  between  the  Gala- 
pagos archipelago  and  Central  America  than  by  the  theories 
hitherto  accepted. 

While  in  general  agreement  with  the  same  views,  Dr. 
Sarasin  §  suggests  that  the  ancient  land  bridge  lay  in  a  north- 
eastward direction,  that  is  to  say,  from  the  Galapagos  islands 
towards  Mexico  rather  than  to  Ecuador. 

The  fossil  marine  mollusks  and  their  distribution  are  em- 
ployed by  Dr.  von  Ihering  ||  in  support  of  the  same  theory. 
He  draws  attention  to  the  remarkable  fact  that  the  species 
of  the  Tertiary  Chilean  deposits  only  appear  on  the  Cali- 
fornian  coast  in  Pleistocene  times,  and  that  similarly  the 
Californian  Tertiary  forms  only  reached  the  coasts  of  Chile 
about  the  same  time.  On  these  grounds  alone  Dr.  von  Ihering 
bases  his  theory  of  a  Tertiary  peninsula  extending  westward 
into  the  Pacific  Ocean  and  embracing  the  Galapagos  islands, 

*  Gadow,  H.,  "  Amphibia  and  Keptiles,"  p.  373. 

t  Gadow,  H.,  "Mexican  Amphibians  and  Keptiles,"  p.  211. 

J  Boettger,  O.,  "  Baur's  Differentiation  of  Species,"  p.  462. 

§  Sarasin,  F.,  "  Die  Fauna  der  Galapagos  Inseln,"  p.  293. 

||  Ihering,  H.  von,  "Fauna  der  Neotropischen  Eegion,"  p.  296. 


314  OKIGIN   OF  LIFE   IN   AMERICA 

which,  thus   acted   as    a    barrier    in    separating    the    North 
American  from  the  South  American  fauna  (see  Fig.  17). 

That  the  distribution  of  reptiles  and  mollusks  on  the  Gala- 
pagos  islands  points  to  a  former  land  connection  with  the 
American  mainland  is  especially  urged  by  Dr.  Arldt,*  but, 
like  Dr.  Ortmann,  he  thinks  the  islands  must  have  been  iso- 
lated since  the  end  of  the  Mesozoic  era.  The  land  connection 
referred  to  is  shown  in  Dr.  Ortmann's  f  map  illustrating  the 
distribution  of  land  and  water  during  the  Upper  Cretaceous 
Period  (Fig.  15). 

As  regards  the  flora,  Messrs.  Kobinson  and  Greenman  con- 
tend that  no  species  to  be  found  on  the  different  islands  illus- 
trates the  noteworthy  racial  divergence  in  related  forms  better 
than  Euphorbia  viminea.  This  species  differs  markedly  in 
foliage  from  any  other  known  member  of  the  large  genus 
Euphorbia  and  is  characteristic  of  the  Galapagos  archipelago. 
Being  essentially  a  desert  plant,  it  can  subsist  even  upon  those 
islands  of  the  archipelago  which  are  of  low  altitude  and  do 
not  attain  the  upper  regions  of  moist  atmosphere.  The  most 
cursory  inspection  of  the  forms  from  the  different  islands 
discloses  marked  variation  in  the  contour,  size,  thickness, 
rigidity  and  colour  of  the  leaves,  as  well  as  in  the  length  of 
the  internodes,  colour  of  the  stems  and  so  forth,  whereas  more 
careful  examination  shows  that  these  are  not  mere  individual 
differences,  due  to  chance,  state  of  development,  or  individual 
environment,  but  that  each  form  appears  in  general  to  be 
restricted  to  a  single  island. 

The  question  consequently  presents  itself,  according  to 
Messrs.  Kobinson  and  Greenman, J  "  If  this  archipelago  is 
composed  of  islands  of  elevation,  built  up  from  the  sea-floor 
independently  by  volcanic  action,  how  has  such  a  distribution 
been  effected?  "  If  the  vegetation  has  been  derived  from  the 
mainland  by  chance  transportation  of  seeds,  it  is  quite  impos- 
sible to  believe  that  each  island  has  received  a  slightly  different 
form  of  the  same  species,  and  we  are  forced  to  the  much  more 
natural  assumption  that  racial  and  varietal  divergence  has 

*  Arldt,  T.,  "  Entwicklung  der  Kontinente,"  p.  116. 
t  Ortmann,  A.  E.,  "  Distribution  of  Decapods,"  p.  381. 
t  Robinson,  B.  L.,  and  J.  M.  Greenman,  "  Galapagos  Flora,"  pp.  135  — 
137. 


EUPHOKBIA  AND   ITS   ORIGIN  315 

come  about  after  the  introduction  of  the  species  on  the  islands. 
Continuing  the  supposition  that  these  are  islands  of  elevation, 
the  seeds  of  Euphorbia  viminea  must  have  reached  them  in 
one  or  two  ways.  Either  every  one  of  the  nine  islands  where 
we  know  the  species  now  to  occur  must  have  received  its  seed 
directly  from  the  mainland,  or,  what  is  much  more  natural, 
seed  must  have  reached  one  or  more  of  the  islands  and  from 
these  have  spread  to  the  rest.  That  the  same  species  should 
have  reached  all  these  islands  presupposes  a  considerable 
facility  of  transportation.  But  as  soon  as  this  is  granted, 
it  is  impossible  to  understand  the  highly  individual  develop- 
ment of  the  forms  on  the  different  islands.  For  relative  or 
complete  isolation  seems  necessary  to  account  for  the  racially 
divergent  floras  of  the  islands,  and  especially  for  the  occur- 
rence of  only  one  form  on  each  island.  On  Dr.  Baur's 
assumption  of  a  former  union  between  the  islands,  and  sub- 
sequent separation  by  subsidence,  the  authors  maintain  that 
not  only  is  an  explanation  of  the  facts  possible,  but  the  exist- 
ing flora  of  the  archipelago  is  just  that  which  would  most 
naturally  result  from  such  an  origin.  A  former  union  of  the 
islands  would  account  at  once  for  the  occurrence  of  identical 
ancestral  species  upon  the  different  members  of  the  group. 
The  subsequent  separation  would  give  the  needed  isolation  for 
varietal  and  racial  divergence,  while  the  latter  could  not  have 
come  about  if  a  continual  interchange  of  seed  were  taking 
place  from  island  to  island. 

Messrs.  Robinson  and  Greenman's  careful  reasoning  is 
just  as  well  applicable  to  the  birds  of  the  genera  Geospiza, 
Certhidea  and  Nesomimus,  to  the  reptilian  genera  Tropidurus 
and  Testudo,  and  to  the  snail  Bulimulus  as  it  is  to  Euphorbia 
viminea,  and  from  a  study  of  any  of  them  we  should  come  to 
precisely  the  same  conclusion  as  these  authors.  Mr. 
Hemsley  *  thinks  the  biological  data  which  we  possess  from 
the  Galapagos  islands  are  strongly  in  favour  of  Professor 
Baur's  views,  and  he  supposes  the  area  on  which  the  islands 
stand  to  have  been  continued  eastward  to  the  mainland  of 
Veraguas. 

Professor  Stewart  does  not  produce  any  new  data  for  or 

*  Hemsley,  W.  Botting,  "  Insular  Floras,"  VI.  (A),  p.  299. 


316  ORIGIN   OF   LIFE  IN   AMERICA 

against  the  theory  of  a  former  land  connection  between  the 
islands  and  the  mainland.  He  scarcely  discusses  the  problem 
from  a  botanical  point  of  view,  but  assumes  that  the  Gala- 
pagos islands  are  of  oceanic  origin.* 

Personally,  I  am  in  agreement  with  Mr.  Andrew  Murray's 
and  Professor  Baur's  theory  that  the  archipelago  originated 
through  subsidence  of  a  land-mass  which  was  connected  with 
the  mainland.  From  the  latter  the  islands  received  the  prin- 
cipal members  of  the  fauna  and  flora,  and  these  progressed 
from  the  one  to  the  other  on  a  solid  land  surface.  Subse- 
quently, possibly  owing  to  volcanic  disturbance,  the  land  sub- 
sided, leaving  only  the  mountain  tops  with  their  animals  and 
plants  as  fragmentary  relicts  of  a  rich  and  varied  fauna  and 
flora.  So  far  I  am  in  agreement  with  Professor  Baur's  theory, 
but  I  believe  that  the  geological  history  of  the  Galapagos 
archipelago  forms  only  part  of  a  much  larger  and  far  more 
complex  problem.  In  the  first  place,  it  is  evident  that  the 
whole  fauna  and  flora  of  the  Galapagos  islands  cannot  have 
originated  in  Central  America  or  the  West  Indies.  A  large 
proportion  of  the  animals  and  plants  seem  to  have  their 
nearest  relations  in  Ecuador  and  Colombia.  Others  point 
to  a  still  more  southern  or  northern  origin.  If  we  derive  the 
fauna  and  flora  principally  from  a  former  land  connection 
with  the  mainland  of  America,  that  connection  must  have  had 
several  branches.  The  affinities  of  the  archipelago  appear 
to  be  chiefly  with  Central  America  and  Ecuador  and  much 
less  with  Chile.  On  the  other  hand,  a  certain  relationship,  for 
instance  among  the  Bulimuli,  exists  with  the  southern  ex- 
tremity of  Lower  California.  All  these  different  areas  of 
North,  Central  and  South  America  may  have  been  joined 
with  the  Galapagos  land-mass  by  peninsulae,  though  one  or 
more  of  them  may  have  become  disconnected  long  before  the 
others.  Dr.  Arldt  f  indicates  something  of  that  kind  in  his 
map  illustrating  the  conditions  of  land  and  water  in  Creta- 
ceous times.  At  least,  he  connects  western  Mexico  and 
Ecuador  by  a  broad  land  bridge  westward  of  Central  America 
and  across  the  area  of  the  Galapagos  archipelago.  I  ventured 

*  Stewart,  A.,  "  Botanical  Survey  of  Galapagos  Islands,"  p.  239. 
t  Arldt,  J.,  "Entwicklung  der  Kontinente,"— Karte  19. 


OKIGIN   OF   GALAPAGOS   FAUNA  317 

to  propound  the  theory  that  North  and  South  America  might 
have  been  joined  by  means  of  a  land  bridge  between  Mexico 
and  Chile  across  the  Galapagos  islands  at  a  time  when  the 
greater  part  of  South  America  was  still  submerged.*  But 
that  land  connection  is  evidently  one  which  must  have  ceased 
to  exist  in  its  entirety,  at  least  in  early  Tertiary  times  (see 
Pig.  16). 

I  have  likewise  alluded  above  to  a  supposed  affinity  of  some 
of  the  Galapagos  birds  to  species  found  in  the  Sandwich 
islands,  pointing  out  that  in  other  groups  this  relationship 
undoubtedly  exists,  although  only  to  a  slight  extent.  I  have 
mentioned  examples  among  the  mollusks.  Among  plants  the 
composite  Lipochaeta  is  a  good  example.  The  genus  is  con- 
fined to  the  Sandwich  islands,  except  one  species  which  in- 
habits the  Galapagos  archipelago.  Instances  of  affinity  of 
the  Sandwich  islands  with  Mexico  and  Central  America  also 
occur,  though  as  a  rule  the  relationship  is  a  remote  one. 
Still,  it  has  been  tentatively  suggested  by  several  writers  that- 
some  time  or  other  in  the  past  Mexico  or  California  were 
joined  by  a  'land  bridge  to  these  islands.  It  might  be  con- 
sidered somewhat  beyond  the  scope  of  this  work  to  discuss  a 
faunistic  relationship  of  this  nature,  but  it  really  forms  part 
of  the  great  problem  as  to  the  origin  of  the  older  Asiatic  stock 
on  the  American  continent. 

What  I  described  above  (p.  97)  as  the  latest  or  most  recent 
immigration  of  Asiatic  types  into  North  America  took  place,  I 
think,  in  Pliocene  and  perhaps  early  Pleistocene  times. 
A  large  proportion  of  the  more  northerly  animals  and  plants 
now  living  in  North  America  readily  reveal  their  Asiatic  origin 
as  slightly  modified  descendants  of  a  stock  once  common  to 
both  .Asia  and  North  America.  These  we  must  regard  as 
the  offspring  of  the  latest  Asiatic  invasion.  The  American 
species  which  thus  indicate  their  Asiatic  lineage  were  des- 
cribed as  Asiatic  invaders  principally  in  the  early  chapters. 
In  the  fourth  chapter  the  time  and  the  place  of  their  invasion 
across  Bering  Strait  were  more  fully  discussed.  Throughout 
the  subsequent  chapters  I  drew  attention  to  the  existence 
of  severally  geologically  more  ancient  invasions  from  Asia,  ex- 

*  Scharff,  R.  F.,  "Early  Tertiary  Land-connection,"  p.  525. 


318  .ORIGIN   OF   LIFE   IN   AMERICA 

pressing  my  belief,  contrary  to  the  opinion  of  almost  all  those 
who  had  occupied  themselves  with  this  problem,  that  these 
earlier  Asiatic  immigrants  took  an  entirely  different  route 
from  the  later  ones.  The  opinion  I  had  formed  was  founded 
on  a  variety  of  circumstances. 

If  the  theory  I  had  formulated  is  correct,  namely  that  the 
effects  presented  by  the  Glacial  Epoch  were  due  to  the 
simultaneous  closing  of  the  Arctic  Ocean  from  the  Atlantic 
and  Pacific  by  the  formation  of  two  land  bridges,  one 
of  which  connected  North  America  with  Europe  in  the 
east,  while  the  other  joined  North  America  and  Asia  in 
the  west  (see  Fig.  7),  the  warmer  climate  in  pre-Glacial 
times  must  have  been  due  to  the  fact  that  the  Arctic 
Ocean  then  received  a  greater  amount  of  heated  water 
than  it  does  now.  That  the  two  land  bridges  must  have  existed 
at  nearly  the  same  time  seems  to  be  amply  demonstrated  from 
biological  evidence.  During  the  Miocene  Period  the  climate 
in  the  extreme  north  of  Europe  and  North  America  must  have 
been  much  milder  than  in  Pliocene  times.  The  evidence  from 
northern  Europe  is  against  the  supposition  that  the  Gulf 
Stream  entered  the  Arctic  Ocean  more  freely  during  the 
Miocene  Period  than  it  does  at  present.  The  Japanese 
"Kuroshiwo,"  or  possibly  some  even  more  powerful  marine 
current,  must  have  passed,  therefore,  entirely  into  the  basin 
of  the  Arctic  Ocean  across  Bering  Strait.  I  remarked  before 
(p.  96)  that  the  appearance  of  certain  Pacific  species  of 
mollusks  in  the  English  Crag  deposits  may  perhaps  be  due 
to  this  cause.  It  was  not  until  Pliocene  times,  according  to 
Professor  J.  P.  Smith,*  that  the  marine  faunas  of  Japan 
and  the  western  coast  of  North  America  began  to  be  re- 
markably similar,  thus  implying  that  a  migration  at  that  time 
took  place  along  a  continuous  shore-line.  The  Californian 
Miocene  marine  deposits  seem  mostly  to  contain  endemic 
species  with  a  slight  admixture  of  southern  and  circumboreal 
ones.  All  this  evidence  favours  the  view  of  an  open  Bering 
Strait  in  Miocene  times,  and  a  closed  one  during  the  Pliocene 
Period.  Dr.  Dall  f  states  that  the  Kenai  leaf  beds  in  Alaska 
(now  generally  considered  of  Eocene  or  Oligocene  age)  are 

*  Smith,  J.  P.,  "  Periodic  Migrations,"  pp.  225—226. 
t  Dall,  W.  H.,  "Correlation  Papers— Neocene,"  p.  251. 


HISTORY  OF   PACIFIC   OCEAN  319 

succeeded  by  Miocene  beds  with  a  marine  fauna.  Similarly 
he  describes  a  series  of  Miocene  marine  mollusks  from  sand- 
stones obtained  at  the  head  of  the  Gulf  of  Penjinsk  on  the 
opposite  shore  of  Asia.  As  in  Alaska,  these  Miocene  sand- 
stones are  apparently  resting  on  leaf-bearing  lignites,  thus 
strengthening  the  assumption  of  a  wide  and  freely  open 
passage  in  the  north,  between  the  Pacific  and  Arctic  Oceans.* 
Professor  Schuchertf  separates  North  America  from  Asia  by 
a  marine  channel  throughout  Miocene  and  Pliocene  times  in 
his  maps  illustrating  North  American  paleogeography.  All 
the  evidence,  says  Mr.  Knopf,J  from  which  conclusions  of 
some  positiveness  can  be  drawn,  record  only  epochs  during 
the  Tertiary  Era  of  more  widely  spread  submergence  and 
increased  separation  of  the  continents.  And  yet  his  exten- 
sive studies  of  the  mammalian  fauna  led  Professor  Osborn  § 
to  the  conclusion  that  the  emergence  of  continents  progressed 
during  the  Miocene  Period  and  that  North  America  was 
broadly  united  with  eastern  Asia.  How  can  wo  reconcile  these 
diametrically  opposite  views  ?  I  have  shown  that  in  Oligo- 
cene  times,  or  during  part  of  that  Period,;  a  trans- Atlantic  land 
connection  probably  enabled  the  Old  World  types  to  travel  to 
North  America.  A  Bering  Strait  land  bridge  is  not  essential, 
therefore,  in  explaining  existing  Oligocene  or  Eocene  affini- 
ties between  the  Old  World  and  the  New.  But  I  have  given  a 
large  number  of  instances  among  North  American  plants  as 
well  as  animals,  indicating  a  direct  migration  either  from  Asia 
to  North  America  or  vice  versa,  in  early  and  late  Tertiary,  at 
any  rate  in  pre-Pliocene  times.  I  need  only  allude  again  to 
the  close  relationship  of  the  hellbender  of  the  eastern  States 
to  the  Japanese  giant  salamander,  of  the  blue-tailed  skink 
of  the  eastern  States  and  Japan,  and  of  the  absolute  identity 
of  the  American  and  Japanese  ground  lizards  (Lygosoma 
laterale) .  The  only  living  relation  of  the  American  alligator 
inhabits  the  Yangtse  river  in  China ;  the  nearest  akin  to  the 
American  green  snakes  (Liopeltis  and  Cyclophis)  reside  in 
south-eastern  Asia.  The  family  of  snapping  turtles  (Chely- 

*  Ball,  W.  H.,  "Miocene  Fauna  in  Arctic  Siberia,"  p.  473. 

t  Schuchert,  C.,  "  Paleogeography  of  North  America,"  Maps  98—100. 

J  Knopf,  A.,  "  Tertiary  Land-connection,"  p.  419. 

§  Osborn,  H.  F.,  "The  Age  of  Mammals,"  p.  244—245. 


320  ORIGIN   OF   LIFE   IN   AMERICA 

dridae)  are  confined  to  America  and  New  Guinea,  the  Aglypha, 
a  division  of  the  Colubrine  snakes,  inhabit  south-eastern  Asia 
and  Papuasia,  except  one  genus  which  is  restricted  to  Central 
America.  The  pythons  are  mainly  Australian  and  southern 
Asiatic,  but  a  single  species  (Loxocemus  bicolor)  lives  in 
southern  Mexico.  The  American  land-snail  Bulimulus,  as 
we  have  seen,  has  its  nearest  relation  (Placostylus)  in 
Australia  and  the  islands  of  the  western  Pacific.  The  geogra- 
phical distribution  of  the  land  isopods  belonging  to  the  group 
of  Spherilloninae,  from  New  Zealand,  Australia,  Polynesia, 
south-eastern  Asia  and  Japan  to  south-western  North 
America,  seemed  to  Mr.  Budde-Lund  *  so  very  peculiar  that 
he  invoked  a  Pacific  continent  to  explain  it.  As  a  matter  of;  fact 
we  have  very  numerous  similar  instances  indicating  a  striking 
faunistic  affinity  between  North  America  and  eastern  Asia. 
But  these  examples  belong  to  an  entirely  different  category 
from  the  animals  and  plants  referred  to  as  forming  the  later 
Asiatic  immigration.  Certain  closely  allied  or  even  identical 
forms  such  as  the  alligator,  the  blue-tailed  skink  and  the 
ground-lizard  in  America  and  eastern  Asia  apparently  point 
to  a  geologically  recent  faunistic  interchange  between  these 
countries.  But  alligators  are  known  even  from  the  earliest 
Tertiary  deposits,  while  the  range  of  the  ground-lizard 
(Lygosoma)  from  New  Zealand,  Australia  and  southern  Asia 
as  far  north  as  Japan,  indicates  that  the  genus  is  probably  of 
Mesozoic  origin,  and  that  we  have  to  deal  with  a  remarkably 
persistent  ancient  type. 

When  we  take  a  general  survey  of  the  range  in  North 
America  of  these  older  Asiatic  animals  (and  the  plants  per- 
fectly agree  with  them),  we  find  that  their  number  decreases 
as  we  go  north -westward,  but  increases  towards  the  south- 
west and  Central  America.  The  whole  stream  of  these  ancient 
Asiatic  immigrants  seems  to  have  issued  forth  from  the  south- 
west, precisely  from  the  same  part  of  North  America  that 
also  yielded  the  European  colonists.  It  is  in  south-western 
North  America,  I  think,  that  we  have  to  search  for  indications 
of  the  older  land  connection  with  Asia,  and  not  in  the  Bering 
Strait.  Another  point  that  strikes  us  during  our  general 

*  Budde-Lund,  G.,  "Kevision  of  Crustacea  Isopoda  Terr.,"  II.,  p.  40 


THEORY  OF  A  PACIFIC  CONTINENT          321 

survey  is  that  the  American  and  Asiatic  forms  related  to  one 
another  are  in  Asia  mainly  confined  to  the  south-eastern 
border  generally,  or  to  Japan.  Australia,  New  Zealand  and 
New  Guinea  also  possess  a  large  number  of  species  and  genera 
very  closely  allied  to  west  American  ones.  These  seem  rarely 
to  extend  further  north  in  Asia  than  Japan.  Are  we  to  throw 
a  bridge  across  the  Pacific  ocean  from  Japan  in  order  to  find  a 
possible  explanation  of  this  former  invasion  of  south  Asiatic 
and  Australian  types  into  western  America,  or  does  any  other 
theory  meet  all  the  facts  of  the  case  ? 

Since  Dr.  Augustus  Gould  *  first  mooted  the  hypothesis  of 
a  former  Pacific  continent  about  sixty  years  ago,  the  idea  has 
been  widely  discussed  by  biologists  and  geologists.  Mr. 
Murray's  f  attention  seems  to  have  been  first  drawn  to  the 
subject  by  the  occurrence  of  the  beetle  Meristhus  scrobinula 
in  Mexico  and  China,  and  by  the  presence  of  the  mole  Urotri- 
chus  in  California  and  Japan.  The  Japanese  and  Californian 
moles  are  no  longer  placed  into  the  same  genus,  but  no  one 
doubts  that  the  American  Neiirotrichus  and  Japanese  Urotri- 
chus  are  very  nearly  related  to  one  another  and  that  they 
must  have  had  a  common  ancestor. 

The  supporters  of  the  theory  of  the  permanence  of  our  great 
ocean  basins  explain  such  cases  by  means  of  a  former  Bering 
Strait  land  bridge,  but,  as  already  stated,  the  solution  of  this 
problem  must  be  sought  elsewhere.  That  several  of  the  pre- 
mises on  which  the  theory  of  the  permanence  of  ocean  basins 
is  founded  are  incorrect  has  been  demonstrated  (pp.  274 — 
277).  Darwin's  theoretical  considerations  on  the  formation 
of  coral  reefs  and  atolls,  which  demanded  a  long  continued 
subsidence  of  the  mid-Pacific  region,  have  been  amply  veri- 
fied. To  put  his  subsidence  theory  to  a  practical  test  Darwin 
suggested  that  a  boring  should  be  made  into  one  of  the  cores 
of  an  atoll.  Through  the  perseverance  aoid  energy  of  Pro- 
fessor Sollas  J  and  Professor  Edgworth  David  a  boring  on 
Funafuti  atoll  was  carried  to  a  depth  of  one  thousand  one 
hundred  and  fourteen  feet,  where  cores  were  obtained  showing 

that  the  whole  mass  of  rock  was  composed  of  pure  coral.  Since 
» 

*  G-ould,  A.,  "  Kemarks  on  Mollusks,"  p.  78. 

t  Murray,  A.,  "  Geographical  Eelations  of  Coleopterous  Faunas,"  p.  37. 

t  Sollas,  W.  J.,  "The  Atoll  of  Funafuti." 
L.A.  Y 


322  ORIGIN   OF   LIFE  IN  AMERICA 

the  organisms  that  form  coral  reefs  are  unable  to  live  at  a 
greater  depth  than  one  hundred  and  fifty  feet,  it  is  manifest 
that  the  floor  of  the  ocean  must  have  subsided  very  slowly 
and  continuously,  thus  enabling  the  reef-building  corals  to 
raise  their  structures  to  the  requisite  depth  of  water.  The 
verdict  of  Funafuti  is  thus  clearly  and  unmistakably  in  favour 
of  Darwin's  theory  of  subsidence.  The  fact  that  a  slight  local 
elevation  seems  to  be  taking  place  in  some  parts  in  no  way 
detracts  from  the  truth  which  has  been  so  firmly  established. 

It  would  lead  me  too  far  from  my  main  object  to  allude  to 
the  numerous  papers  that  have  been  written  on  the  Pacific 
Continent  controversy.  After  Gould  and  Murray  it  was 
Captain  Hutton,*  I  think,  who  again  revived  the  theory,  which 
he  later  on  discussed  in  his  presidential  address  to  the  Philo- 
sophical Institute  of  Canterbury  in  New  Zealand.  His  idea 
was  that  New  Zealand,  eastern  Australia  and  India  formed  one 
biological  region  in  early  Mesozoic  times.  In  Lower  Cre- 
taceous times  a  large  Pacific  Continent  extended  from  New 
Guinea  to  Chile,  and  from  the  latter  a  long  lobe  of  land 
stretched  southward  to  New  Zealand.  This  Pacific  Continent, 
in  his  opinion,  supported  plants,  insects,  snails,  frogs,  some 
lizards,  perhaps  snakes  and  a  few  birds,  but  no  mammals. 
Later  on,  during  the  Cretaceous  Period,  New  Zealand  became 
separated,  while  the  Pacific  Continent  broke  up. 

More  recently  Dr.  von  Iheringf  alluded  to  a  Pacific  Con- 
tinent which  he  believes  to  have  gradually  subsided  during 
the  Mesozoic  Era,  but  without  going  into  further  details  as 
to  its  nature  and  size.  I  may  mention  that  the  supposed 
antarctic  land  connection  between  Patagonia  and  New  Zea- 
land is  a  subject  which  I  am  not  dealing  with  at  present. 
Dr.  Pilsbry  assailed  the  problem  entirely  from  the  point  of 
view  of  the  molluscan  distribution.  He  points  out  that  many 
genera  of  land-snails  reach  back  to  the  Oligocene  Period 
unchanged  save  in  specific  characters,  and  that  the  modern 
family  groups  of  these  snails  undoubtedly  diverge  far  back 
in  Mesozoic  time.  Now  it  is  a  most  significant  fact  that  the 
Pacific  islands  are  almost  entirely  tenanted  by  the  most  primi- 

*  Hutton,  F.  W.,  "  Origin  of  Fauna  and  Flora  of  New  Zealand." 
t  Ihering,   H.   von,    "Eelations  between    New  Zealand  and   South 
America,"  p.  444. 


THEORY  OF  A  PACIFIC   CONTINENT          323 

tive  and  oldest  groups  of  land-snails.  And,  as  Dr.  Pilsbry 
facetiously  puts  it,  "it  is  very  easy  to  show  that  snails  may 
have  been  carried  from  place  to  place  by  a  hurricane,  a  float- 
ing tree  or  '  floating  island/  or  that  their  eggs  may  find  room 
in  the  pellet  of  earth  clinging  to  a  bird's  feather,  but  it  is  in- 
cumbent upon  the  theorist  who  peoples  the  mid-Pacific  islands 
by  such  means  to  show  why  such  dominant  groups  as  the  Heli- 
cidae,  Bulimulidae,  Bhytididae,  Streptaxidae — in  fact  the 
whole  Holopoda  and  Agnathomorpha,  with  the  higher  mem- 
bers of  the  aulacopod  families,  as  well  as  the  higher  opercu- 
lates — should  have  utterly  failed  to  take  advantage  of  these 
means  of  transport."  Instead  of  being  a  faunal  dependency  of 
the  Australian  or  Oriental  regions,  Polynesia  has  every  ap- 
pearance, says  Dr.  Pilsbry,  of  being  a  region  which  started 
with  a  fauna  long  antedating  the  present  Australian  and 
Oriental  faunas,  developing  along  its  own  lines,  retaining  old 
types  because  they  did  not  come  into  competition  with  the 
higher  groups  of  animal  life.  Dr.  Pilsbry's  conclusion  is  that 
a  Pacific  Continent  existed,  which  was  finally  separated  from 
other  lands  as  early  as  the  middle  of  the  Mesozoic  Era,  and 
that  the  northern  portion  became  disconnected  when  the 
remainder  was  still  joined  to  the  mainland.* 

A  careful  review  of  the  distribution  of  the  ants  and  lizards 
in  particular  led  Professor  Baur  f  to  formulate  the  theory 
of  a  former  Indo-Pacific  Continent  extending  from  Malaysia 
to  the  west  coast  of  America.  He  looked  upon  the  Pacific 
islands  as  the  last  remnants  of  this  continent,  which  still 
existed,  he  thinks,  until  the  commencement  of  the  Miocene 
Period. 

Mr.  Hedley,$  who  took  part  in  the  famous  Funafuti  Ex- 
pedition, and  has  had  the  advantage  of  studying  the  problems 
of  dispersal  on  the  spot,  altogether  disbelieves  in  a  Pacific 
Continent  in  the  sense  of  Baur,  Pilsbry  and  Button,  but  he 
suggests  that  New  Zealand  was  formerly  connected  with  Aus- 
tralia by  way  of  New  Caledonia,  the  New  Hebrides,  Solomon 
islands  and  New  Guinea.  Even  the  Fiji  islands  come  within 
this  scheme.  Some  years  earlier  he  had  already  demonstrated 


*  Pilsbry,  H.  A.,  "  Genesis  of  Mid-Pacific  Faunas,"  pp.  569—578. 
|  Baur,  G.,  "New  Observations  on  the  Galapagos  Islands,"  p.  869. 
|  Hedley,  C.,  "  Zoogeographic  Scheme,"  pp.400 — 405. 

Y2 


324  OKIGIN  OF   LIFE   IN   AMERICA 

the  essential  unity  of  the  area  inhabited  by  the  snail  Placo- 
stylus,*  thus  regarding  New  Zealand  and  the  archipelagoes  of 
Solomon,  Fiji,  New  Hebrides,  Loyalty,  New  Caledonia  and 
Lord  Howe  as  portions  of  a  shattered  continent  which  he 
called  the  "  Melanesian  plateau."  The  short  review  on  the 
subject  by  Dr.  Holdhausf  in  favour  of  a  Pacific  Continent  in 
Tertiary  times  adds  little  to  the  arguments  already  advanced 
by  Professor  Baur. 

A  most  determined  and  thoroughgoing  onslaught  on  the 
theory  of  a  supposed  former  Pacific  Continent  was  recently 
made  by  Mr.  Guppy.    It  seems  scarcely  fair  to  compare  the 
results  of  his  studies  with  those  just  alluded  to,  because 
he  derives  his  arguments  almost  altogether  from  the  flora 
of  the  Pacific  islands,   while  the  others   were  founded   on 
faunistic  data.      Still,  Mr.  Guppy' s  works  J  contain  a  great 
deal   of   personal   observation,   and   his    careful   labours   in 
this   particular   field   of    enquiry    will    be    sure    to    attract 
the   serious  attention  of  the   student  of   geographical  dis- 
tribution.    His  discussion  of  the  subject  is  disappointing! 
in    some    respects.      "  If  the   distribution    of    a    particular 
group  of  plants  or  animals  does  not  accord  with  the  pre- 
sent arrangement  of  the  land,"  he  remarks,  "  it  is  by  far 
the  safest  plan,  even  after  exhausting  all  likely  modes  of 
explanation,  not  to  invoke  the  intervention  of  geographical 
.changes."     A  little  further  he  explains  "  I  scarcely  think 
that  our  knowledge  of  any  one  group  of  organisms  is  ever 
sufficiently  precise  to  justify  a  recourse  to  hypothetical  altera- 
tions in  the  present  relations  of  land  and  sea."    In  reading 
such   passages   one  wonders  whether  Mr.  Guppy  can  have 
become  acquainted  with  the  science  of  geology,  or  with  the 
principles   that   underlie   the  geographical  distribution,  for 
example,  of  mammals.  His  opinions  differ  radically  even  from 
those  of  Dr.  Wallace,  who  cannot  be  said  to  have  been  unduly 
rash  in  any  of  his  conclusions  as  to  former  changes  of  land 
and  water.    One  would  also  expect  from  Mr.  Guppy  an  abun- 
dance of  important  facts  concerning  the  dispersal  of  seeds 
by  the  various  means  of  accidental  transport.    But  he  tells  us 

*  Hedley,  C.,  "  Eange  of  Placostylus,"  p.  339. 

t  Holdhaus,  K.,  "  Argumente  f.  d.  Existens  eines  pazif.  Kontinents." 

t  Guppy,  H.  B.,  "  A  Naturalist  in  the  Pacific,"  I.,  p.  380. 


GUPPY  ON   PACIFIC   CONTINENT  325 

that  the  story  of  plant  distribution  in  the  Pacific  is  bound 
up  with  the  successive  stages  of  decreasing  activity  in  the 
dispersing  agencies.  He  thinks  that  the  area  of  active  dis- 
persion, as  illustrated  by  the  non-endemic  genera  of  plants, 
at  first  comprised  the  whole  of  the  tropical  Pacific.*  After- 
wards it  was  limited  to  the  southern  Pacific,  and  finally  to  the 
western  Pacific  only.  The  birds  that  carried  seeds  all  over  this 
ocean  became  more  and  more  restricted  in  their  range,  pro- 
bably, as  Mr.  Guppy  suggests,  on  account  of  increasing 
diversity  of  climatic  conditions.  The  plants  of  necessity  re- 
sponded to  the  ever  narrowing  conditions  of  bird-life  in  this 
ocean,  the  differentiation  of  the  plant  and  bird  taking  place 
together. 

Mr.  Guppy  dislikes  the  idea  of  hypothetical  alterations  in 
the  present  relations  of  land  and  water,  and  yet  what  an 
amount  of  hypothesis  he  has  to  resort  to  in  his  endeavour  to 
explain  the  theory  which  he  is  so  anxious  to  support !  There 
is  not  a  scrap  of  evidence  for  the  belief  that  dispersing 
agencies  have  practically  ceased  at  the  present  time,  nor  that 
the  migrations  of  birds  have  diminished.  On  the  contrary, 
ornithologists  have  done  their  utmost  to  trace  the  origin  of 
all  bird  migrations  to  the  gradually  increasing  diversity  of 
climatic  conditions  during  the  Tertiary  Era,  which  they  sup- 
pose to  have  culminated  in  the  Glacial  Epoch.  Although  we 
have  little  evidence  for  such  a  belief,  it  seems  a  reasonable 
supposition.  But  what  can  be  said  in  favour  of  Mr.  Guppy's 
theory,  that,  owing  to  the  increasing  diversity  of  climatic  con- 
ditions, the  seed-carrying  birds  have  become  more  restricted, 
that  is  to  say,  less  migratory  ? 

A  careful  perusal  of  Mr.  Guppy 's  work  must  make  it  evident 
to  anyone,  that,  although  plants  have  far  greater  facilities  for 
accidental  transport,  and  have  in  many  cases  actually  been 
thus  conveyed  from  one  land  surface  to  another,  they  agree 
on  the  whole  perfectly  with  animals,  in  so  far  as  the  Pacific 
islands  are  largely  tenanted  by  very  ancient  types.  If  we  adopt 
the  theory  of  accidental  dispersal  for  the  origin  of  the  Pacific 
island  flora,  we  must  apparently  assume  that  the  means  of 
occasional  conveyance  were  far  more  efficient  in  former  times 

*«  Guppy,  H.  B.,  "A  Naturalist  in  the  Pacific,"  IL,  pp.  519—520. 


326  ORIGIN   OF   LIFE   IN   AMERICA 

than  they  are  at  present.  Even  Mr.  Guppy,  however,  some- 
times relents  and  partly  withdraws  from  his  precepts  when 
confronted  by  really  difficult  cases  of  distribution.  Thus  he 
acknowledges  that  the  conifer  Dammara  vitiensis,  which  grows 
on  the  Fiji  islands,  is  unfitted  for  accidental  dispersal  by  any 
of  the  known  modes  of  conveyance.  The  genus  Dammara  is 
confined  to  New  Zealand,  eastern  Australia,  New  Caledonia, 
the  New  Hebrides  and  Fiji  islands.  From  this  region  it  ex- 
tends westward  to  Java  and  Borneo,  the  centre  of  distribution 
being  in  the  western  Pacific.  The  absence  of  the  genus  from  the 
neighbouring  Samoan  and  Tongan  groups  is,  as  Mr.  Guppy  * 
remarks,  very  significant,  and  it  is  evident  that  the  ordinary 
agencies  of  dispersal  by  birds,  winds  or  currents  have  here 
failed  to  extend  Dammara  over  a  few  hundred  miles  of  sea. 
For  once  Mr.  Guppy  concedes,  therefore,  that  the  present 
relations  of  land  and  sea  do  change  sometimes,  and  that, 
"  nolens  volens,"  we  must  admit  that  Dammara  may  well  be 
cited  in  support  of  any  continental  hypothesis  affecting  the 
western  Pacific.  Later  on,  in  fact,  he  expresses  the  opinion 
that  the  Fiji  islands  mark  the  site  of  a  Mesozoic  continental 
area  in  this  region. 

There  is  thus  a  certain  amount  of  distributional  evidence 
in  favour  of  the  theory  of  the  existence  of  a  large  land  sur- 
face in  the  western  Pacific.  Whether  the  remainder  of  that 
ocean  was  ever  completely  occupied  by  land  is  a  more  difficult 
question  to  answer.  But  even  on  the  distant  Marquesas 
islands  granites  and  gneisses  occur,  as  I  mentioned  before. 
In  the  tuffs  of  the  Kermadec  islands  numerous  boulders  of 
hornblende  granite  have  been  found.  New  Caledonia  consists 
of  an  ancient  series  of  mica  schists  and  slates  with  a  general 
north-easterly  strike.  There  are  also  shales  containing  fossils 
identical  with  those  of  the  New  Zealand  Trias,  followed  by  beds 
of  coal  of  Jurassic  age.  Gneisses,  crystalline  limestones  and 
serpentines,  like  those  of  New  Caledonia,  are  reported  from  the 
New  Hebrides.  Crystalline  schists,  granular  limestone, 
granite,  diorite  and  gabbro  have  been  discovered  on  the  Fiji 
islands.  The  occurrence  on  the  Tonga  group  of  fragments 
of  garnet,  tourmaline  and  uralitic  gabbro  suggests  the  close 

*  Guppy,  H.  B.,  "  A  Naturalist  in  the  Pacific,"  II.,  pp.  297—306, 


DAEWIN'S  THEOKY  OF  COKAL  REEFS   327 

proximity  of  an  area  of  metamorphic  rocks,  while  a  series  of 
plutonic  rocks  have  recently  been  described  from  Tahiti. 

Thus,  according  to  Mr.  Speight,*  there  appears  to  be  geo- 
logical evidence  of  the  former  extension  of  continental  con- 
ditions over  a  large  area  of  the  mid-Pacific  region.  As  he 
remarks,  it  is  highly  probable  that  many  volcanic  islands 
classified  as  oceanic  will  ultimately  have  to  be  looked  upon 
as  built  up  on  the  remnants  of  a  continental  area.  We  may 
imagine  that  a  large  land  area  or  continent  covered  the  greater, 
part  of  the  present  Pacific  Ocean  in  Palaeozoic  and  early 
Mesozoic  times,  and  that  there  was  a  subsidence  during  later 
Mesozoic  and  Tertiary  times  with  more  recent  local  elevations. 

Professor  Haug,f  discusses  the  Pacific  problem  from 
another  point  of  view.  His  studies  of  the  geosynclinals,  which 
he  calls  the  essentially  mobile  regions  of  the  earth's  crust, 
led  him  to  the  conclusion  that  the  circumpacific  geosynclinal 
implied  the  former  existence  of  a  continent  in  place  of  the 
present  Pacific  Ocean. 

The  well-known  parallelism  of  the  different  groups  of  Pacing 
islands  has  likewise  been  utilised  in  support  of  the  same 
theory.  It  may  be  explained  by  the  supposition  that  these 
islands  are  either  the  remnants  or  the  initial  stages  of  a 
series  of  mountain  chains.  J  The  Funafuti  boring  results  seem 
to  point  to  the  first  of  these  as  the  more  likely  assumption. 

That  Darwin's  theory  of  subsidence  still  meets  with  a  good 
deal  of  determined  opposition  by  the  believers  of  the  per- 
manence of  ocean  basins  may  be  gauged  from  Sir  John 
Murray's  writings  on  the  structure  and  origin  of  coral  reefs. 
I  think  it  is  unnecessary  for  me  to  discuss  the  bearings  of  his 
arguments  on  the  American  problems  raised  in  this  chapter, 
because,  in  the  first  place,  it  seems  probable  that  both  Mur- 
ray's hypothesis  of  elevation  and  Darwin's  of  subsidence  may 
be  applicable  to  certain  cases,  and,  secondly,  because  a  Pacific 
continent  in  the  sense  of  Hutton,  Pilsbry  and  Baur  cannot 
evidently  be  cited  in  support  of  most  of  the  older  Tertiary 
affinities  between  Asia  and  North  America  that  I  have  alluded 

*  Speight,  E.,  "  Petrological  Notes  on  Eocks  from  Kermadec  Islands," 
pp.  244—250. 

f  Haug,  E.,  "  Geosynclinaux  et  aires  continentales,"  p.  646. 
J  Arldt,  T.,  "  Parallelismus  d.  Kiisten  v.  Sudamerika." 


328  OKIGIN   OF   LIFE   IN   AMEEICA 

to.     If  a  Pacific  continent  existed,  and  I  quite  concur  with 
those  who  are  of  that  opinion,  it  must  have  largely  subsided 
before   the   Tertiary  Era.     It  seems  to  me  as  if  the  central 
part  of  it  had  broken  down  gradually,  the  margins  slowly 
following  suit,  both  on  the  eastern  and  western  Pacific,  only 
leaving  here  and  there  a  few  remnants  which  either  remain 
as  isolated  pillars  far  out  in  the  ocean  or  have  become  joined 
to  more  recent  land-masses.     I  imagine  that  the  latest  pre- 
Pliocene  land  connection  between  North  America  and  Asia  was 
not  the  Pacific  Continent,  but  merely  its  margin,  which  per- 
sisted probably  until  Oligocene  or  Miocene  times.    In  a  geo- 
logical sense,  remarks  Dr.  von  Drasche,*  it  is  more  correct 
to  draw  the  western  boundary  of  the  Pacific  Ocean  through 
Kamchatka,  Japan,  the  Philippines,  New  Guinea  and  New 
Caledonia,  because  they  all  possess  old  crystalline  or  ancient 
sedimentary  rocks.     But  the  oceans,  as  Professor  Walther  f 
has  pointed  out,  are  areas  of  depression  surrounded  by  folds  or 
flexures  which  give  rise  to  extravasation  of  eruptive  material. 
The  chain  of  the  volcanic  Aleutian  islands  lie  in  such  a  fold. 
Near  the  east  coast  of  Japan  the  depth  greatly  increases.    On 
the  eastern  side  of  the  Pacific,  in  western  North  America, 
the  igneous  rocks  skirt  the  coast  for  some  distance,  whereas 
in  the  south-west  the  volcanic  centres  lay  far  inland,  justi- 
fying the  assumption  that  the  Tertiary  coast-line  extended 
some  distance  inland,  which  is  fully  established  by  geological 
observation.    Although  the  Pacific  is  known  to  have  invaded 
Californian  territory,  there  is  no  evidence  that  the  coast  hills 
and  outlying  islands  were  covered  by  the  sea ;  and  these  pro- 
bably remained  as  part  of  the  marginal  land  which  skirted  the 
west  coast  of  North  America.    It  is  from  this  old  land,  I  think, 
which    contained    Asiatic    immigrants,  that  North  America 
received  its  ancient  Tertiary  fauna  from  Asia.     I  suggest, 
therefore,  that  in  early  Tertiary  times  a  belt  of  land,  possibly 
representing  the  margin  of  the  more  ancient  Pacific  Continent, 
extended  from  the  south-west  coast  of  North  America  in  a 
great  curve  to  Japan  and  further  south  (see  Fig.  14).     The 
extraordinary  similarity  of   the   east  Asiatic,  Mesozoic  and 

*  Drasche,  E.  von,  "  Palaeozoische  Schichten  auf  Kamtschatka,"  p.  268. 
t  Walther,  J.,  "  Uber  den  Bau  der  Flexuren,  &c." 


NOETH  PACIFIC   LAND   BKIDGE  329 

early  Tertiary  marine  faunas  to  those  of  California  would 
thus  receive  a  satisfactory  explanation  without  invoking  a 
land  connection  across  Bering  Strait.  As  soon  as  the  marine 
channel  which  separated  the  coast  hills  in  California  from  the 
rest  of  the  country  disappeared,  a  number  of  Asiatic  immi- 
grants entered  North  America.  But  the  flora,  especially  of  the 
small  islands  lying  off  the  coast  of  California,  still  bears  the 
impress,  as  Mr.  Greene*  has  pointed  out,  of  belonging  phyto- 
geographically  to  another  continent  than  America. 

I  also  mentioned  'that  the  European  invasion  of  North 
America,  which  travelled  by  the  trans -Atlantic  land  bridge, 
had  ultimately  entered  the  Continent  from  the  south-west. 
The  two  elements,  the  Asiatic  and  the  European,  must  have 
joined  there  eventually.  To  judge  from  purely  faunistic  testi- 
mony, that  was  evidently  the  course  of  events  (compare 
p.  211).  Somewhere  about  the  Miocene  Period  extensive  sub- 
sidence of  the  land  west  of  California  must  have  compelled 
the  fauna  and  flora  to  seek  refuge  on  the  continent  with  which 
the  Pacific  belt  of  land  seems  to  have  become  united.  Palaeon- 
tological  evidence  gives  us  reason  for  such  a  supposition.  Take 
for  example  the  great  land-tortoises.  Their  sudden  appearance 
in  south-western  Miocene  deposits  suggests  that  they  came 
from  the  west  with  other  new-comers.  This  hypothesis  like- 
wise throws  light  on  their  survival  near  at  hand  in  the  Gala- 
pagos islands,  which  no  doubt  once  formed  part  of  the  Pacific 
belt  of  land  alluded  to.  There  are  such  a  variety  of  problems 
connected  with  this  theory  that  I  shall  defer  the  further  dis- 
cussion of  it  till  the  next  chapter.  In  conclusion,  a  few  addi- 
tional remarks  on  the  nature  of  the  supposed  extension  of  land 
west  of  Central  America  will  facilitate  the  comprehension  of 
the  scheme  of  land  connections  that  have  only  been  roughly 
outlined  so  far. 

When  I  described  the  remarkable  fauna  and  flora  of  the 
Cape  region  of  Lower  California  (p.  207)  and  their  marked 
affinities  to  those  of  the  opposite  coast  of  Mexico,  I  made  no 
reference  to  the  fact  that  this  interesting  assemblage  of 
animals  and  plants  is  living  in  a  hilly  district  being  separated 
from  the  nearest  mountains  to  the  north  of  it  by  a  wide  extent 

*  Greene,  E.  L.,  "  Botany  of  Santa  Cruz  Island,"  pp.  377—388. 


330  OKIGIN   OF   LIFE   IN  AMERICA 

of  a  low -lying  plain.  This  district,  moreover,  is  entirely 
granitic  and  composed  of  a  number  of  high  ridges  running 
parallel  in  an  east- westerly  direction,  the  remainder  of  the 
great  peninsula  being  largely  formed  of  calcareous  rocks  with 
mountain  ranges  running  in  a  north  and  south  direction. 
Between  the  two  lies  a  great  plain  several  hundred  miles  long 
with  a  height  of  scarcely  one  hundred  and  fifty  feet  above  sea- 
level.  The  two  mountain  ranges  manifestly  belong  to  entirely 
different  systems,  and  the  junction  between  the  two  must  have 
been  a  comparatively  recent  geological  event.  Mr.  Eisen* 
was  so  much  impressed  by  the  supposed  severity  of  the  climate 
during  the  Glacial  Epoch  that  he  believed  the  whole  Cape 
region  was  at  that  time  wrapped  in  snow  and  ice  and  devoid  of 
animal  life.  But  he  also  contends  that  it  must  have  been  an 
island  and  that  during  its  rise  animals  and  plants  gradually 
reached  it  from  the  mainland  by  accidental  transport.  That 
the  Cape  Region  has  only  recently  become  part  of  Lower  Cali- 
fornia is  highly  probable.  To  judge  from  the  fauna  and  flora, 
it  must  have  been  connected  by  land  with  some  part  of  Central 
America  or  southern  Mexico,  though  it  possesses  affinities,  too, 
with  Asia  and  the  Pacific  islands  (compare,  p.  208).  Rather 
more  than  half-way  across  the  sea  between  the  Cape  Region 
and  the  south  coast  of  Mexico  lies  the  small  group  of  tihe 
Tres  Marias  islands,  and  it  might  be  argued  that  they 
had  once  formed  the  connecting  link  between  the  mainland 
and  that  faunistically  so  remarkable  Cape  Region  of  Lower 
California.  The  animals  and  plants  of  these  islands,  how- 
ever, although  clearly  showing  that  the  islands  have  been 
joined  to  one  another  and  to  southern  Mexico,  exhibit  no 
near  relationship  to  those  of  the  Cape  Region.}  Hence  it 
is  probable  that  the  faunistic  and  floristic  affinity  between 
the  Cape  Region  and  southern  Mexico  is  due  to  the  fact 
that  both  regions  have  acquired  their  animals  and  plants,  in 
more  remote  times,  from  the  same  source  in  Central  America. 
I  suggested  in  a  former  chapter  (p.  287)  that  the  moun- 
tains of  Guatemala  had  once  extended  further  westward. 
Guatemala  certainly  seems  to  have  been  a  land  surface 

*  Eisen,  G.,  "  Explorations  in  the  Cape  Region,"  p.  735. 
t  Nelson,  E.  W.,  L.  Stejneger,  and  others,  "  Natural  History  of  the 
Tres  Marias  Islands." 


SUNKEN   PACIFIC   LAND  331 

since  very  remote  geological  times,  while  its  ancient  moun- 
tain system,  trending  in  a  west-eastward  direction,  abruptly 
terminates  on  the  Pacific  coast.  I  ventured  to  explain 
the  many  instances  of  curiously  discontinuous  distribution 
in  Central  America  by  the  supposition  that  an  ancient  land 
occupied  the  adjoining  portion  of  the  Pacific,  and  that  the 
present  Central  America  is  partly  formed  of  the  remnants  of 
that  land  having  eventually  become  moulded  together  by  geo- 
logically recent  volcanic  deposits.  If  we  assume  that  the  Cape 
Kegion  of  Lower  California  belonged  to  that  Pacific  land 
which  really  formed  the  southern  continuation  of  the  north 
Pacific  belt  of  land  alluded  to,  a  reasonable  explanation  is 
advanced  for  the  faunistic  affinity  of  the  Cape  Kegion  to 
Central  America,  the  West  Indies  and  Asia,  and  its  dissimi- 
larity with  the  rest  of  Lower  California.  The  hypothesis  of  a 
former  westward  continuation  of  portions  of  Central  America 
is  not  founded  purely  on  zoogeographical  considerations. 
In  his  reference  to  the  older  Tertiary  sediments  of  Central 
America  Professor  Hill*  states  that  it  is  impossible  to  avoid 
the  conclusion  that  they  were  derived  from  a  near-by 
land  which  existed  at  the  time  of  their  deposition.  The  only 
hypothesis,  he  says,  that  can  fit  the  condition  of  their 
present  lay  and  arrangement  is  that  this  land  existed 
towards  the  Pacific  coast  or  in  the  area  now  covered  by  the 
Pacific  waters  of  the  Isthmian  Eegion.  The  "  old  land  " 
or  early  representative  of  the  isthmus  of  Panama,  remarks 
Mr.  Hershey,f  lay  mainly  south  of  the  present  isthmus. 
That  it  was  a  land-mass  of  considerable  extent,  he  con- 
tinues, is  indicated  by  the  heavy  beds  of  conglomerate 
formed  from  it,  and  he  argues  that  the  peninsula  of  Azuero 
which  projects  out  into  the  Pacific  is  a  remnant  of  this  land, 
while  on  its  northern  border  were  laid  down  the  more  recent 
formations  which  make  up  the  main  body  of  the  isthmus. 
Geologically  there  is,  therefore,  some  evidence,  too,  for  the 
assumption  of  a  former  extensive  land  surface  on  the  Pacific 
side  of  Central  America.  It  must  be  remembered  that  while 
Central  America  as  a  whole  has  a  south-east  and  north-west 


*  Hill,  E.  T.,  "  Geological  History  of  Panama,"  p.  263. 

t  Hershey,  0.  H.,  "  Geology  of  Isthmus  of  Panama,"  p.  249, 


332  OKIGIN   OF   LIFE   IN   AMERICA 

trend  the  isthmus  of  Panama  runs  in  an  east-westward  direc- 
tion. 

That  this  Pacific  land  persisted  to  some  extent  until  com- 
paratively recent  geological  times,  seems  to  be  indicated  by 
several  notable  features.  When  Mr.  Agassiz  surveyed  the 
ocean  floor  from  the  steamer  "  Albatross,"  he  found  the  Pacific 
side  of  Panama  faunistically  poor  compared  with  the  Atlantic 
side,  but  he  attributed  that  condition  to  the  absence  of  a  great 
oceanic  current  on  the  south  side  of  the  isthmus.  The  absence 
of  deep-sea  corals  on  the  Pacific  side  was  most  striking.  Yet, 
he  remarks  that  there  is  on  the  west  coast  of  Central  America, 
oven  in  deep  water,  a  considerable  fauna,  which  finds  its 
parallel  in  the  West  Indies  and  recalls  later  Cretaceous  times 
when  the  Caribbean  Sea  was  practically  a  bay  of  the  Pacific. 
This  assumption  that  the  Caribbean  Sea  was  once  a  bay  of 
the  Pacific  has  been  put  forward  by  other  writers.  The 
faunistic  resemblance,  or  parallelism,  as  we  might  call  it, 
between  the  seas  on  each  side  of  Central  America  may  be  due 
to  a  former  westward  extension  of  the  Atlantic  Ocean  just 
as  much  as  to  an  eastward  extension  of  the  Pacific.  However, 
one  of  the  most  remarkable  features  brought  to  light  by  the 
"  Albatross "  expedition  was  the  condition  of  the  ocean 
floor.  There  was  not  a  station  between  Acapulco,  on  the 
coast  of  Mexico,  and  the  Galapagos  islands,  according  to 
Mr.  Agassiz,  of  which  the  bottom  could  be  characterised  as 
(strictly  oceanic.  At  the  most  distant  points  from  the 
shore  the  bottom  specimens  invariably  showed  some  trace  of 
admixture  of  terrigenous  material.  All  the  way,  even  to  a 
depth  of  2,000  fathoms,  the  trawl  became  filled  with  a  sticky 
mud  containing  logs  of  wood,  branches,  twigs  and  decayed 
vegetable  matter.  Being  a  firm  believer  in  the  permanence 
of  ocean  basins,  Mr.  Agassiz  *  naturally  attributed  this  extra- 
ordinary condition  of  the  sea  floor  to  the  existence  of  currents, 
which,  striking  Central  America  from  north  and  south,  are 
reflected  in  a  westward  direction.  He  likewise  argues  from 
this  discovery  that  it  offers  a  very  practical  object  lesson  re- 
garding the  manner  in  which  the  Galapagos  islands  received 
their  fauna  and  flora.  The  peculiar  condition  of  the  ocean 

*  Agassiz,  A.,  "Keportson  'Albatross'  Expedition,"  pp.  11—77. 


AFFINITIES   OF   TWO  OCEANS  333 

floor  may,  I  think,  be  explained  in  an  entirely  different  way. 
We  might  possibly  expect  a  condition  such  as  Mr.  Agassiz 
describes  off  the  mouths  of  the  Amazon  or  Orinoco  rivers,  but 
there  are  no  vast  rivers  anywhere  on  the  Pacific  coast  to  fur- 
nish all  this  vegetable  detritus  he  speaks  of.  A  similar  condi- 
tion, moreover,  occurs  only  to  a  very  limited  extent  on  the 
Atlantic  side  of  the  isthmus.  That  the  ocean  floor  is  covered 
with  tree  trunks,  twigs  and  other  vegetable  detritus  may  be 
due  to  the  existence  within  recent  geological  times  of  a  well- 
timbered  land  between  Central  America  and  the  Galapagos 
islands  which  has  since  vanished  beneath  the  ocean. 

And  yet  that  all  was  not  land  on  the  Pacific  side  of  Central 
America  is  proved  by  many  distinct  lines  of  evidence. 

Mr.  Guppy  *  tells  us  that  Laguncularia  racemosa,  Ehizo- 
phora  mangle,  Anona  paludosa  and  Conocarpus  erectus,  all 
of  which  are  plants  of  the  mangrove  formation,  occur  not 
only  on  the  Pacific  and  Atlantic  coasts  of  America,  but  also 
on  the  west  coast  of  Africa.  We  cannot  suppose  that  such 
characteristic  sea-shore  species  can  be  conveyed  across  a  land 
area  by  any  known  means  of  accidental  dispersal.  Moreover, 
since  that  vegetation  does  not  occur  south  of  the  Bay  of  Guaya- 
quil, it  could  not  have  reached  the  coast  of  Ecuador  from 
eastern  South  America  by  travelling  round  Cape  Horn.  Thus 
the  most  likely  explanation  of  the  occurrence  of  the  flora  on 
both  sides  of  Central  America  is  to  assume  the  existence  of 
a  former  continuous  shore  line  between  Ecuador  and  Vene- 
zuela. 

In  the  list  of  stalk-eyed  Crustacea  found  on  the  coast  of 
Peru,  Miss  Eathbun  f  reports  that  a  few  species  of  crabs,  like 
Acanthonyx  petiverii,  Micrqphrys  platysoma,  Panopeus  ber- 
mudensis  and  Geograpsus  lividus,  are  common  to  both  sides 
of  Central  America,  while  a  most  striking  feature  is  the 
faunistic  uniformity  of  the  marine  area  between  the  Cape 
Kegion  of  Lower  California  and  the  coast  of  Chile.  Dr. 
DallJ  divided  this  whole  fauna  into  two  provinces,  viz.,  the 
Panamic,  extending  from  Lower  California  to  Guayaquil,  and 
the  Peruvian,  from  the  latter  to  the  island  of  Chiloe  in  Chile, 

*  Guppy,  H.  B.,  "  A  Naturalist  in  the  Pacific,"  p.  498. 
t  Eathbun,  M.  J.,  "  Stalk-eyed  Crustacea  of  Peru." 
t  Ball,  W.  H.,  "Report  on  the  Shells  of  Peru,"  p.  185. 


334  OKIGIN   OF   LIFE   IN   AMERICA 

but  the  two  have  many  forms  of  mollusks  in  common,  and 
should  be  regarded  perhaps  as  sub-divisions  of  one  faunistic 
marine  area.  According  to  Dr.  von  Ihering,*  Chile  received, 
in  early  Tertiary  times,  certain  tropical  genera  of  mollusks 
which  never  succeeded  in  attaining  the  North  American 
coasts,  yet  are  represented  also  in  Patagonia,  while  others, 
such  as  Conus,  Purpura,  Oliva,  Concholepas,  Cassis,  Cypraea 
and  Bissoa  are  absent  from  the  latter  country.  They  are 
supposed  to  have  travelled  along  the  north  coast  of  South 
America  to  Ecuador,  Peru  and  Chile  by  means  of  a  Central 
American  marine  channel.  Certain  species  even  of  that  an- 
cient marine  migration  have  persisted  to  the  present  day, 
not  only  on  the  coast  of  Chile,  but  on  the  west  coast  of  Africa 
and  in  the  Mediterranean.  Even  in  Miocene  times  the  in- 
fluence of  the  Caribbean  and  European  marine  faunas  was 
felt  on  the  coa-st  of  Peru,  according  to  Dr.  Ortmaam.f 
Certain  northern  species  of  the  genera  Saxidomus  and 
Chlorostoma,  says  Dr.  von  Ihering  (p.  524)  did  not  reach  the 
coast  of  Chile  until  the  Pleistocene  Period.  Thus  it  seems 
manifest  that  during  practically  the  whole  of  the  Tertiary 
Era  there  was  no  Humboldt  current  sweeping  northward 
along  the  west  coast  of  South  America,  as  it  does  at  present. 
On  the  contrary,  there  is  sufficient  evidence  to  show  that 
whatever  current  there  existed  flowed  in  the  opposite 
direction. 

This  investigation  has  resulted  in  two  very  important 
results,  viz.,  firstly,  the  demonstration  that  the  Humboldt 
current  formerly  did  not  exist,  and  secondly,  that  its  absence 
must  have  been  caused  by  profound  differences  in  the  condi- 
tions of  land  and  water  from  those  now  prevailing.  Of  the 
nature  of  these  changes  I  have  foreshadowed  already  enough 
to  enable  anyone  to  reconstruct  them.  When  the  currents 
issued  from  the  Caribbean  Sea  into  what  is  now  the  Pacific, 
they  must  have  been  faced  by  land  westward  and  northward. 
They  could  only  have  flowed  southward.  But  the  land  which 
lay  south-westward  between  Central  America  and  the  Gala- 
pagos islands  extended  probably  far  southward,  parallel  to 

*  Ihering,  H.  von,  "  Mollusques  fossiles  de  1' Argentine,"  pp.  514—516. 
t  Ortmann,  A.  E.,  "  Tertiary  Invertebrates  of  Sta.  Cruz,"  p.  320. 


THE  HUMBOLDT  CUEKENT        335 

the  present  coast.  How  far  it  reached  will  be  more  fully  dis- 
cussed in  the  subsequent  chapters.  It  may  only  compara- 
tively recently  have  subsided.  Ma.y  not  the  remarkable  cir- 
cumstance, alluded  to  by  Dr.  Bigelow,*  that  to  the  south-west 
and  west  of  the  Humboldt  current  the  sea  is  almost  entirely 
devoid  of  surface  as  well  as  bottom  life,  be  due  to  this 
cause  ? 

*  Bigelow,  H.  B.,  "  Albatross  Expedition— Medusae,"  p.  222. 


CHAPTEE  X11I 

NORTHERN    STATES   OF   SOUTH   AMERICA 

THE  great  continent  of  South  America  (Fig.  18),  with  its 
roughly  triangular  shape,  is  not  much  smaller  than  its 
northern  relative.  The  basis  of  the  triangle  facing  northward 
is  bounded  by  the  Caribbean  Sea,  and  the  two  other  sides 
by  the  Atlantic  and  Pacific  Oceans  respectively.  There  is 
a  very  general  impression  that  the  west  coast  of  South 
America  is  mountainous,  the  remainder  being  a  vast  plain. 
This  is  not  quite  correct.  A  northern  continuation  of 
the  long  chain  of  the  Andes  skirts  also  the  southern  shores 
of  the  Caribbean  Sea,  while  to  the  south-east  of  it  lies  the 
highland  of  Guiana  and  further  south  the  Brazilian  highland. 
The  two  eastern  highlands — that  of  Guiana  and  Brazil — are 
broken  into  two  parts  by  the  Amazon  valley.  The  space 
between  these  eastern  highlands  and  the  Andes  is  occupied 
by  the  central  lowlands.  We  might  say,  therefore,  that  the 
three  great  natural  regions  of  South  America  are  the  eastern 
highlands,  the  central  lowlands  and  the  western  Cordillera. 
The  Amazon,  Orinoco  and  La  Plata — the  three  great  streams 
— all  drain  eastward. 

The  main  part  of  the  continent  has  a  tropical  climate. 
Sub-tropical  and  temperate  conditions  prevail  in  the  south. 
The  climate  of  the  Brazilian  region  is  exceptionally  favour- 
able for  a  luxuriant  development  of  the  fauna  and  flora, 
whereas  certain  parts  of  what  Dr.  Wallace  called  "  the  Chilean 
sub-region  "  are  arid,  and  inimical  to  expansion  and  specific 
differentiation  of  animals  and  plants. 

Although  our  acquaintance  with  the  fauna,  flora  and 
geology  of  this  vast  continent  is  naturally  much  less  complete 
than  that  of  North  America  or  Europe,  we  possess  unmis- 
takable evidences  of  the  fact  that  South  America  has  under- 
gone considerable  alterations  in  the  distribution  of  land  and 


Highland  over  1500 R 
Upland  over  600  F* 
l_OWlandunder600Fl 


FIG.  18. — Map  of  South  America.     (Reproduced  from  Meiklejohifs  Oroscopic 
Map,  by  permission  of  Messrs.  Meiklejohn  <k  Son.) 


[To  face  p.  336. 


HISTOEY  OF   SOUTH   AMERICA  337 

water  sine©  the  close  of  the  Mesozoic  Era.  The  testimony  is 
of  a  threefold  character.  It  is  founded  on  our  knowledge  of 
geology,  of  palaeontology,  and  of  the  geographical  distribu- 
tion of  living  animals  and  plants.  Eichness,  as  Dr.  Wallace 
observed,  combined  with  isolation,  is  the  predominant  feature 
of  neotropical  zoology.  Nevertheless,  he  thinks  that  early 
during  the  Tertiary  Era,  the  zoological  differences  between 
the  Nearctic  and  Neotropical,  that  is  to  say,  between  the  North 
and  South  American  regions,  were  probably  even  more  radical 
than  they  are  now.  South  America,  he  argues,  was  then  a 
huge  island  or  group  of  islands — a  kind  of  Australia  of  the 
New  World — chiefly  inhabited  by  the  imperfectly  organised 
group  of  edentate  mammals.  Dr.  Wallace  *  believes,  more- 
over, that  there  must  have  been  one  or  more  ancient  Ian4 
connections  between  the  two  continents,  perhaps  in  Eocene 
or  Miocene  times,  admitting  ancestral  types  of  monkeys  and 
the  members  of  the  camel-tribe  (Llamas)  from  the  north  to 
South  America. 

Dr.  Wallace's  opinions,  expressed  thirty-five  years  ago, 
were  founded  entirely  on  the  distribution  of  living  animals. 
Eapid  strides  have  been  made  since  that  time  in  our  know- 
ledge  of  the  fauna  of  South  America.  The  geology  of  certain 
districts  is  being  worked  out.  Botanists  have  made  great 
progress  in  mapping  out  the  distribution  of  plants,  while  the 
most  astonishing  discoveries  have  been  disclosed  principally 
among  the  past  inhabitants  of  the  continent.  Thus  we  are 
now  in  a  very  different  position  from  that  of  Wallace,  when 
he  pronounced  upon  the  physical  changes  of  South  America 
during  the  past,  on  the  strength  of  his  zoological  know- 
ledge. 

We  are  particularly  indebted  to  T)r.  von  Ihering's  re- 
searches on  the  fauna  and  flora  of  South  America,  which  he 
conducted  during  many  years  of  devoted  labour,  that  our  in- 
formation on  the  main  features  of  distribution  has  advanced 
so  rapidly.  During  his  long  residence  in  southern  Brazil  he 
collected,  and  is  still  collecting,  data  bearing  principally  orx 
the  question  of  the  geological  history  of  the  continent;  and 
since  his  scattered  papers  have  recently  been  reprinted  in' 

*  Wallace,  A.  E.,  "  Distribution  of  Animals,"  II.,  p.  58. 

L.A.  Z 


338  OKIGIN  OF  LIFE   IN   AMEEICA 

book  form  we  are  better  able  to  appreciate  the  advances  in  our 
knowledge  that  are  due  to  his  investigations.  His  researches 
were  not  confined  to  recent  zoology.  He  has  also  dealt  with 
the  subject  from  a  palaeontological  point  of  view,  and  has 
even  subjected  the  main  features  of  the  flora  to  a  detailed 
revision.  All  the  same,  he  acknowledges  that  there  are  several 
important  problems  connected  with  the  geological  history  of 
South  America  for  which  no  satisfactory  solution  has  as  yet 
been  suggested.  More  than  twenty  years  ago,  Dr.  von  Ihering 
announced  that  the  close  relationship  of  the  Brazilian  with 
the  African  fresh -water  mussels  implied  the  former  existence 
of  a  land  connection  between  South  America  and  Africa. 
But,  whereas  America  as  a  whole  is  one  of  the  richest  regions 
for  fresh-water  mussels  in  the  world,  Chile  an'd  Peru  are 
among  the  poorest.  While  east  of  the  Andes  there  is  a 
luxuriant  fauna  of  fresh-water  mussels  largely  related  to  that 
of  Africa,  we  find  only  the  genus  Unio  (in  its  wide  sense)  re- 
presented on  the  western  slope  of  the  mountains.  Dr.  von 
Ihering  explains  this  and  other  similar  facts  by  the  supposi- 
tion that  in  the  east  and  the  west  there  were  originally  similar 
faunas,  but  while  eastern  South  America  obtained  a  rich  stock 
of  immigrants  across  the  land  bridge  from  Africa,  the  great 
mountain  chain  of  the  Andes,  which  was  then  commencing 
to  rise,  prevented  any  further  influx  westward.  Considering 
that  the  fresh- water  mussels  (Unionidae)  are  well  represented 
even  in  Jurassic  deposits,  Dr.  von  Ihering*  recognised  that  the 
geographical  distribution  of  these  mollusks  may  be  utilised 
to  advantage  as  indicators  of  very  ancient,  especially 
Mesozoic,  conditions  of  land  and  water. 

In  the  course  of  his  studies  the  same  author  came  to  the 
conclusion  that  from  the  Cretaceous  to  the  end  of  the  Pliocene 
Periods,  South  America  must  have  been  completely  separated 
from  North  America.  A  real  South  American  continent 
existed  only  since  Oligocene  times.  It  then  consisted  of  two 
parts  united  by  the  narrow  isthmus  of  the  newly  formed 
Andes.  He  named  these  two  old  original  constituents  of 
South  America  "  Archiguiana  "  and  "  Archiplata."  The 
former  comprised  the  highlands  of  Guiana  and  Venezuela, 

*  Ihering,  H.  von,  "  Archhelenis  and  Archinotis,"  p.  79. 


FAUNISTIC  ELEMENTS  339 

the  latter  the  remainder  of  South  America,  the  two  parts 
being  separated  by  a  broad  ocean  except  for  a  narrow  western 
land  bridge.  Each  of  these  great  islands  had  its  own  peculiar 
fauna  and  flora,  but  Archiguiana  must  have  been  connected 
by  land  with  Africa  until  Oligocene  times,  and  Archiplata 
with  New  Zealand  and  Australia  during  the  Mesozoic 
Era,  !  ;  I  I  . 

With  the  gradually  increasing  knowledge  of  palaeontology 
Dr.  von  Ihering's  original  ideas  naturally  became  subject  to 
various  modifications.  Thus  in  a  map  representing  the  con- 
ditions of  land  and  water  during  the  Eocene  Period,  and  pub- 
lished in  1907  (Fig.  17),  not  Archiguiana  but  Archiplata  is 
connected  by  land  with  Africa  and  also  India,  the  whole  of 
this  ancient  continent  being  called  "  Archhelenis."  Archi- 
plata is  still  joined  at  this  time  to  Australia  by  means  of  the 
antarctic  continent  "  Archinotis,"  while  Archiguiana  is 
united  with  the  West  Indies  and  parts  of  Central  America 
into  a  large  land-mass  which  stretched  forth  westward  to  the 
Sandwich  islands,  and  was  called  "  Pacila."  Quite  recently 
the  same  author  brought  forward  testimony  in  favour  of  a 
Miocene  land  bridge  between  Central  America  and  eastern 
Asia.  I  have  already  alluded  to  it  in  the  previous  chapter. 
Dr.  von  Ihering  now  tells  me  that  he  will  shortly  publish 
a  revised  palaeogeographical  map  in  the  "  Neues  Jahrbuch 
fur  Mineralogie  und  Geologie,"  in  which  these  features  are 
indicated.  i 

The  same  problem,  studied  from  the  point  of  view  of  the 
distribution  of  fresh-water  crabs  and  crayfishes,  led  Dr. 
Ortmann*  to  somewhat  different  conclusions.  At  the  end 
of  the  Mesozoic  Era  he  recognises  the  existence  of  the  island 
of  Brazil,  which  had  previously  been  connected  with  Africa, 
while  Guiana  was  still  joined  to  western  North  America  on  the 
one  hand  and  Africa  on  the  other.  The  independent  Chilean 
tract  of  land  was  connected  with  Australia  by  means  of  the 
supposed  antarctic  continent  (Fig.  15).  At  the  commence- 
ment of  the  Tertiary  Era  South  America  had  assumed  its 
present  shape,  except  for  an  elongated  bay  extending  inland 
from  the  Atlantic  Ocean  into  the  valley  of  the  Amazon.  In 

*  Ortmann,  A.  E.,  "Distribution  of  Decapods,"  pp.  379—381. 

z2 


340  ORIGIN   OF   LIFE   IN   AMERICA 

the  south  it  was  still  joined  to  the  Antarctic  Continent,  which 
had  then  become  separated  from  Australia.  In  the  north  it 
had  lost  its  land  connection  with  North  America,  which  it  did 
not  regain  until  later  Tertiary  times. 

To  a  certain  extent  the  views  of  the  two  authors  agree,  at 
any  rate,  in  the  assumption  that  the  continent  of  South 
America  is  composed  of  several  originally  independent  land- 
masses,  one  of  which  was  joined  to  Africa.  The  most  striking 
difference  in  their  opinions,  apart  from  the  geological  period 
during  which  the  various  elements  are  supposed  to  have  be- 
come fused  together,  lies  in  Dr.  Ortmann's  conception  of 
three  totally  distinct  land-masses,  while  Dr.  von  Ihering  only 
recognises  two.  Nevertheless,  even  the  latter  acknowledges 
the  faunistic  division  of  his  "  Archiplata  "  into  a  northern 
and  southern  portion,  although  his  nomenclature  is  apt  to  be 
somewhat  confusing.  Dr.  von  Ihering  informs  us  (p.  177) 
that  the  old  Archiplata  fauna  has  no  close  relationship  to 
that  of  the  rest  of  South  America. 

A  third  contribution  to  the  geological  history  of  South 
America  is  furnished  by  another  group  of  fresh-water  animals, 
namely,  the  fishes.  The  tropical  American  fresh-water  fauna, 
having  its  centre  of  greatest  diversity  in  the  middle  Amazon 
basin,  says  Professor  Eigenmann,*  is  attenuated  northward 
till  it  reaches  the  vanishing  point  just  on  the  borders  of 
the  United  States.  Southward  it  extends  to  somewhere  south 
of  Buenos  Aires.  The  Patagonian  and  North  American 
faunas  are  entirely  different  from  the  tropical  American  fauna 
and  from  each  other.  The  results  of  his  studies  are  that  the 
existing  distribution  of  the  fresh-water  fishes  can  only  have 
been  brought  about  by  the  supposition  that  tropical  America 
in  early  Tertiary  times  consisted  of  two  land  areas  ("  Archi- 
guiana  "  and  "  Archamazona  "),  separated  by  the  lower  valley 
of  the  Amazon,  which  was  submerged  by  the  sea.  There  was 
a  land-mass  between  Africa  and  South  America,  possibly 
joining  Guiana  and  tropical  Africa.  But  this  connection,  he 
urges,  must  have  ceased  to  exist  before  the  origin  of  the 
present  genera,  and  even  before  that  of  some  of  the  families. 

*  Eigenmann,  0.  H.,  "Freshwater  Fishes  of  South  America,"  pp.|517 
—528. 


GEOLOGY  OF    SOUTH   AMERICA  341 

Several  other  writers  have  discussed  the  theory  of  former 
land  bridges  between  South  America  and  Africa  and  between 
South  America  and  other  continents  without  dealing  with  the 
geological  history  of  South  America  itself.  Their  views  will 
be  presented  later  on. 

The  only  author  who,  to  my  knowledge,  has  treated  the 
subject  under  review  from  a  purely  palaeontological  stand- 
point is  Dr.  Ameghino.  His  views  were  brought  for- 
ward in  several  important  technical  papers.  As  they  may 
have  undergone  slight  modification  in  the  course  of  time,  I 
prefer  to  quote  his  opinions  from  a  recent  semi-popular 
account.  It  may  be  mentioned  that  Dr.  Ameghino's  * 
theories  are  founded  on  the  known  distribution  of  fossil 
mammals.  North  of  the  Equator,  he  says,  there  was,  at  the 
end  of  the  Mesozoic  Era,  a  vast  ocean  containing  many 
islands.  In  the  south  lay  a  great  continent,  united  in  the 
east  with  Africa  and  in  the  south  with  Australia  and  New 
Zealand  by  way  of  an  antarctic  land  bridge.  Gradually,  in 
early  Tertiary  times,  the  northern  islands  became  fused  and 
joined  to  the  southern  land -mass,  while  Australia  was  dis- 
connected. During  all  this  time  North  and  South  America 
remained  entirely  separated.  Mammals,  however,  were  able 
to  pass  from  the  latter  continent  through  Africa  into  Europe, 
and  across  a  land  bridge  in  northern  latitudes  to  North 
America.  The  sea,  which  had  covered  the  Andean  region  in 
Mesozoic  times,  disappeared  early  in  the  Tertiary  Era,  but 
certain  bays  of  the  Pacific  Ocean  still  remained  and  ex- 
tended eastward  to  the  far  side  of  the  Andes.  During  the 
Eocene  Period  the  Atlantic  Ocean  advanced  from  the  south, 
covering  part  of  Argentina  and  practically  separating 
Brazil  from  the  rest  of  the  continent,  while  the  former  land 
connection  with  Africa  ceased  to  exist.  Towards  the  end  of 
the  Oligocene  Period  the  "  Archhelenis  "  land  bridge  once 
more  rose  to  the  surface  for  a  brief  period  and  then  finally 
subsided  entirely,  save  for  a  few  scattered  islands. 

It  would  have  been  particularly  valuable  to  obtain  Pro- 
fessor Osborn's  opinions  on  the  geological  evolution  of  South 
America.  We  possess  only  his  palaeogeographical  maps 

*  Ameghino,  Fl.,  "  Geologia  de  la  Republica  Argentina,"  pp.  9—16. 


342  ORIGIN   OF   LIFE -IN   AMERICA 

founded  upon  the  distribution  of  fossil  mammals.  It  is  sur- 
prising that  in  these  maps  South  America  in  late  Cretaceous 
and  basal  Eocene  times,  is  represented  as  almost  precisely 
what  it  is  to-day,  except  that  it  is  continued  southward  across 
an  antarctic  continent  to  Australia.  In  the  middle  Eocene, 
South  America  differs  only  in  so  far  as  a  long  bay  of  the 
Atlantic  has  entered  the  Amazon  valley.  There  are  no  indica- 
tions of  any  land  bridges  at  that  time,  South  America  being 
completely  isolated  from  all  other  continents.  During  the 
Oligocene  Period  it  still  remained  so,  but  the  sea  made 
further  inroads  on  the  Amazon  valley,  it  encroached  on  the 
valley  of  the  Parana  river  and  flooded  a  large  part  of  Argen- 
tina, reducing  southern  Chile  to  a  few  islands.  It  is  only  in 
Miocene  times,  according  to  Professor  Osborn,*  that  South 
America  became  divided  into  two  parts  by  a  broad  gulf  ex- 
tending from  the  Atlantic  to  the  Pacific  across  the  Amazon 
valley. 

Geologists,  except  Dr.  Katzer  and  Professor  de  Lapparont,f 
have  as  a  rule  dealt  with  the  problem  in  a  less  comprehensive 
manner.  The  ideas  of  the  latter  differ  from  the  authors  cited 
in  so  far  as  the  main  permanent  land -mass  at  the  end  of  the 
Mesozoic  Era  in  South  America  was  confined,  in  their  opinion, 
to  the  east.  They  suppose  the  highlands  of  Guiana,  eastern 
and  southern  Brazil  to  have  been  united.  All  the  rest  of  the 
continent  was  then  under  water.  At  the  commencement  of 
the  Eocene  Period,  according  to  Professor  de  Lapparent, 
Central  America  had  come  into  existence,  but  disappeared 
again  shortly  after,  while  a  broad  marine  channel  stretched 
from  the  Pacific  to  the  Atlantic  between  northern  Chile  and 
Argentina.  Dr.  Katzer's  views  are  somewhat  similar.  He 
dees  not  believe  in  the  Atlantic  Ocean  having  invaded  South 
America  from  the  east.  In  the  beginning  of  the  Mesozoic  Era 
the  area  of  archaean  rocks  and  later  palaeozoic  deposits  of 
Guiana  and  Brazil  formed  a  large  connected  land-mass.  In 
Upper  Jurassic  times,  he  says,  the  old  land  connection  be- 
tween South  America  and  South  Africa  on  the  one  hand,  and 
between  South  America  and  Australia,  still  existed.  An  old 

*  Osborn,  H.  F.,  "Age  of  Mammals"  Maps,  pp.  64,  137,  183  and  245. 
t  Lapparent,  A.  de,  "Traite  de  Geologic,"  4th  ed.,  pp.  1376  and  1455. 


DEVELOPMENT   OF   SOUTH  AMERICA         343 

ocean  strait  extended  from  the  north  side  of  Guiana  across 
Venezuela  and  Colombia  to  Peru  during  the  Cretaceous 
Period.  During  all  this  time,  and  even  in  early  Tertiary 
times,  the  waters  from  the  old  eastern  land  continued  to 
drain  westward  towards  the  Pacific.  The  persistent  rise  of 
the  newly  formed  Andean  mountain  chain  resulted  at  first 
in  the  formation  of  a  vast  lake  covering  the  entire  lowlands 
of  the  Amazon  valley  area.  Eventually,  in  Miocene  times, 
according  to  Dr.  Katzer,*  the  drainage  was  reversed,  with  the 
result  that  the  Amazon  river  flowed  for  the  first  time  into  the 
Atlantic  Ocean.  Concurrently  North  and  South  America  be- 
came united  through  the  Central  American  land  bridge. 

Professor  Koken's  f  palaeogeographical  maps  were  con- 
structed as  the  outcome  of  a  combination  of  geological  and 
palaeontological  studies.  South  America,  he  remarks,  had 
already  assumed  its  present  shape  and  form  in  Cretaceous 
times,  though  it  did  not  extend  so  far  west  as  at  present  except 
in  Ecuador  and  Colombia.  It  was  separated  from  all  other 
continents  but  Africa.  In  early  Tertiary  times  South  America 
became  entirely  isolated.  Argentina  and  southern  Chile  were 
largely  flooded  by  the  sea,  while  a  long  gulf  filled  the  whole 
valley  of  the  Amazon  as  far  east  as  the  Andes. 

Dr.  Arldt,  J  who  included  the  distribution  of  living  animals 
and  plants  as  well  as  palaeontology  within  the  sphere  of  his 
studies,  gives  a  series  of  highly  complex  maps  which  cannot 
readily  be  described.  His  conception  is  that  South  America 
in  Lower  Cretaceous  times  was  somewhat  like  that  described 
by  Professor  Koken,  viz.,  an  extension  of  land  eastward  as  far 
as  Africa  and  a  simultaneous  submergence  of  the  west  coast. 
Towards  the  end  of  the  Mesozoic  Era,  that  is  to  say  at  the  end 
of  the  Cretaceous  Period,  a  complete  change  in  the  conditions 
of  land  >and  water  supervened.  South  America  was  then 
divided  into  two  parts  by  an  interoceanic  connection  across 
the  Amazon  valley.  The  northern  portion,  consisting  of 
Colombia,  Ecuador  and  Guiana,  is  supposed  to  have  extended 
westward  across  the  Galapagos  islands  as  far  as  the  Sandwich 

*  Katzer,  F.,  "  Geologie  des  Amazonengebietes,"  pp.  239—262. 

t  Koken,  E.,  "  Die  Vorwelt,"  Maps  1  and  2. 

I  Arldt,  J.,  "  Entwicklung  der  Kontinente,"  Maps  19  and  20. 


344  OKIGIN   OF  LIFE  IN  AMERICA 

islands,  thus  forming  a  great  peninsula  of  land  which  like- 
wise was  joined  to  lower  California  and  western  Mexico.  The 
southern  part  of  South  America  was  then  still  united  by  a 
narrow  land  bridge  with  Africa,  while  the  western  side  of  it 
now  became  joined  to  a  great  belt  of  land  extending  right 
across  the  Pacific  Ocean  to  New  Zealand  and  Australia.  In 
early  Tertiary  times  South  America  became  separated  from 
North  America  and  the  Sandwich  islands,  while  the  two 
sections  of  the  continent  fused  in  the  west.  The  African 
and  Australian  land  connections  still  persisted  in  a  modified 
form. 

We  can  gather  from  all  these  expressions  of  opinion  as  to 
the  past  geological  history  of  South  America  that  there  is 
comparatively  little  general  agreement  on  the  subject.  Some 
points,  however,  seem  to  be  fairly  well  established.  All 
authorities  concur  in  the  belief  that  the  Eastern  highlands  of 
Guiana  and  Brazil  have  been  land  surfaces  since  the  begin- 
ning of  the  Secondary  Era,  at  any  rate,  and  on  these,  there- 
fore, we  ought  to  find  relicts  of  a  Mesozoic  fauna.  All  the 
writers  quoted  also  agree  that  at  some  time  or  other  during 
the  Tertiary  Era  there  was  either  a  complete  interoceanic 
connection  along  the  Amazon  valley  or  a  long  gulf  of  the  ocean 
extending  for  some  distance  inland.  Yet  there  is  an  im- 
portant difference  of  opinion  as  to  whether  this  gulf  belonged 
to  the  Atlantic  or  the  Pacific  Ocean.  But  since  most  of  the 
writers  contend  that  the  central  portion,  at  any  rate,  of  the 
Andes  is  made  up  largely  of  Jurassic  and  Cretaceous  marine 
deposits,  while  the  eastern  parts  of  South  America  were  land 
in  Mesozoic  times,  it  seems  more  reasonable  to  assume,  with 
Dr.  Katzer,  that  the  Pacific  Ocean  extended  eastward  as  far 
as  the  archaean  highlands  of  Brazil  and  eventually  retreated 
so  as  to  leave  only  a  Pacific  gulf  on  the  site  of  the  existing 
upper  Amazon  valley.  In  view,  however,  of  the  fact  that  the 
Pacific  Ocean  must  have  been  completely  shut  out  from  South 
America  by  the  western  belt  of  land  above  alluded  to,  .it  was 
really  the  waters  of  the  Atlantic  Ocean  which  flooded  western 
South  America  as  far  east  as  the  highlands  of  Brazil  (com- 
pare Fig.  14). 

Several  of  the  authors  cited  recognise  a  faunistic  relation- 
ship between  Australia  as  well  as  between  Africa  and  South 


DEVELOPMENT   OF   SOUTH  AMERICA        345 

America,  and  some  contend  that  Chile  has  been  wholly  or  par- 
tially above  the  surface  of  the  ocean  since  very  early  geological 
times.  As  Professor  Suess  *  has  pointed  out,  the  extreme 
south  of  the  continent  is  composed  of  a  peculiar  and  probably 
very  ancient  system  of  rocks.  This  Patagonian  mountain 
chain  is  quite  independent  of  the  Andes,  of  which  it  does  not 
form  a  continuation.  Further  north  in  Chile  it  lies  outside  or 
westward  of  the  Andes,  constituting  the  coast  Cordillera. 

Still  further  north,  in  Peru,  only  fragments  of  this  Cor- 
dillera are  recognisable  here  and  there  close  to  the  coast, 
while  in  Ecuador  the  ancient  coast  Cordillera  again  appears 
to  be  more  clearly  represented.  There  is  some  evidence, 
therefore,  of  the  existence  of  a  very  old  land -mass  not  only  on 
the  eastern  but  also  on  the  western  side  of  the  continent.  And 
it  seems  as  if  the  Mesozoic  rocks  forming  a  large  part  of  the 
Andes  had  been  deposited  in  a  great  trough  along  the  eastern 
shores  of  this  ancient  land.  When  the  Andes  were  subse- 
quently raised,  the  older  western  land  presumably  subsided, 
leaving  only  here  and  there  along  the  coast  some  traces  of  its 
former  existence. 

Let  us  now  pursue  this  subject  from  a  purely  zoogeo- 
graphical  point  of  view,  and  endeavour  to  utilise  groups  with 
whose  distribution  we  are  fairly  well  acquainted,  in  elucida- 
ting the  more  obscure  points  in  the  geological  history  of 
northern  South  America.  Groups  of  animals  of  which  we 
have  reason  to  believe  that  they  are  very  ancient,  possibly 
of  Mesozoic  age,  will  be  best  for  this  purpose.  Such  a  one  for 
example  is  that  of  the  Onychophora  (Protracheata).  It 
contains  creatures  caterpillar-like  in  appearance,  with  a  beau- 
tifully soft  skin  and  unjointed  limbs.  Internally  they  contain 
air-tubes  so  characteristic  of  insects ;  at  the  same  time,  their 
excretary  organs  resemble  those  of  worms.  These  very  pri- 
mitive features,  taken  together  with  a  wide  and  most  discon- 
tinuous distribution,  have  always  caused  these  creatures  to 
be  looked  upon  as  survivors  or  relicts  of  very  remote  geological 
ages.  Formerly  they  were  all  classified  under  the  genus 
Peripatus.  In  recent  years  many  new  forms  have  been  dis- 
covered and  subjected  to  careful  study,  with  the  result  that 

*  Suess,  E.,  "  Antlitz  der  Erde,"  I.,  pp.  666—690. 


346  OKIGIN   OPi-.LIFE   IN  AMERICA 

quite  a  number  of  genera  are  now  recognised.  The  most 
exhaustive  account  of  these  remarkable  creatures  is,  no  doubt, 
the  monograph  recently  published  by  Professor  Bouvier.  He 
divides  the  group  into  seven  genera,  of  which  Peripatus  is 
confined  to  tropical  and  sub-tropical  America  and  tropical 
Africa,  and  Opisthopatus  to  Chile  and  South  Africa.  This  is 
a  most  astounding  discovery.  That  a  group  of  these  creatures 
found  in  tropical  South  America  should  be  more  closely  related 
to  another  occurring  in  tropical  Africa  than  to  that  of  Chile, 
and  that  the  latter  should  exhibit  a  more  intimate  affinity  with 
South  African  forms  than  with  tropical  American  ones,  is  of 
great  zoogeographical  interest.  Professor  Sedgwick,*  however, 
does  not  share  Professor  Bouvier's  opinion  with  regard  to 
the  intimate  relationship  supposed  to  exist  between  the 
tropical  South  American  and  tropical  African,  and  between 
the  Chilean  and  South  African  groups.  He  thinks  they  are 
perfectly  distinct  from  one  another.  On  the  other  hand,  he 
agrees  with  Professor  Bouvier  in  the  recognition  of  a  group  of 
Onychophora,  limited  to  tropical  and  sub -tropical  America,  as 
distinct  from  the  Chilean  group.  And  this  is  really  the  prin- 
cipal point  I  wish  to  draw  attention  to. 

Professor  Bouvierf  claims  that  the  Andean  species  of  Peri- 
patus are  the  most  primitive  members  of  the  whole  family. 
He  believes  that  the  ancestral  stock  inhabited  a  former  Pacific 
continent,  and  that  their  immediate  descendants  took  refuge 
on  the  eastern  and  western  land  areas  when  their  original 
habitat  vanished.  The  whole  genus  Peripatus,  as  defined  by 
Professor  Bouvier,  I  may  mention  again,  is  found  from 
Mexico  in  the  north,  throughout  Central  America,  the  West 
Indies  ,and  South  America  as  far  south  as  Bolivia.  The 
Chilean  species  belongs,  according  to  the  same  authority,  to 
the  distinct  genus  Opisthopatus. 

The  genus  Peripatus  is  readily  divisible  into  two  sections, 
the  Andean  and  the  Caribbean  one.  The  twelve  species  be- 
longing to  the  former  all  inhabit  the  Pacific  side  of  the  Andes, 
except  Peripatus  eiseni  and  Peripatus  goudoti,  which  live  in 
Mexico  nearly  two  thousand  miles  north-westward  of  the  other 

*  Sedgwick,  A.,  "Distribution  of  Onychophora,"  pp.  383 — 406. 
t  Bouvier,  E.  L.,  "  Onychophores,"  I.,  pp.  64 — 79. 


PEEIPATUS   IN   SOUTH  AMEEICA  347 

members  of  the  Andean  group.  This  discontinuous  distribu- 
tion is  a  very  noteworthy  fact,  for  it  cannot  be  explained  by 
the  supposition  that  some  member  of  this  Andean  group  may 
still  exist  and  have  been  overlooked  in  the  intermediate  vast 
tract  of  country,  because  many  specimens  of  Peripatus  have 
been  discovered  in  Costa  Bica,  Nicaragua  and  Panama,  all 
belonging  to  the  Caribbean  group.  Accidental  dispersal,  such 
as  marine  currents,  cannot  be  invoked  as  being  responsible  for 
this  distribution.  It  is  due,  in  my  opinion,  to  a  former  direct 
land  connection  between  western  Mexico  or  Guatemala  and 
some  part  of  the  west  coast  of  Soutli  America.  That  the 
mountain  system  of  Guatemala  suddenly  terminates  at  the 
edge  of  the  Pacific,  and  that  it  formerly  had  a  westward 
continuation,  has  been  alluded  to,  and  I  have  mentioned  also 
several  cases  of  discontinuous  distribution  that  I  thought 
were  due  to  the  existence  of  an  ancient  land,  more  or  less  in- 
dependent of  Central  America.  The  newt  Spelerpes  is  one 
of  these.  Its  headquarters  seem  to  be  in  Mexico.  A  few  occur 
in  Guatemala,  Costa  Eica  and  Chiriqui.  Further  south  we 
meet  with  the  genus  again  in  Colombia,  Ecuador  and  northern 
Peru,  but  nowhere  else  in  South  America.  The  tortoise 
Chelydra  rosignoni  occurs  in  ^Guatemala.  It  is  absent  from 
the  rest  of  Central  America,  yet  in  Ecuador  we  find  an  isolated 
colony.  Another  tortoise,  Geoemyda  punctularia,  inhabits 
Guatemala  and  Mexico.  Southward  it  is  only  known  from 
Ecuador,  Colombia,  Venezuela  and  further  east.  The  gecko- 
like  genus  Eublepharus  is  probably  an  exceedingly  ancient 
one,  its  range  being  most  peculiar  and  strikingly  western. 
One  species  occurs  in  California,  another  in  Mexico,  still 
another  in  Panama,  and  lastly  one  in  Ecuador.  All  the  re- 
maining species,  which  show  great  resemblance  to  the 
American  ones,  are  confined  to  southern  Asia.  We  probably 
have  to  deal  in  this  case  with  a  persistent  type  which  through- 
out many  geological  periods  has  retained  the  same  characters 
and  has  died  out  in  the  still  existing  land  fragments  of  the 
ancient  Pacific  continent,  whence  it  originally  spread  east 
and  west  after  its  subsidence.  There  are  numerous  other 
examples,  particularly  among  plants,  implying  that  the  land 
which  I  described  as  lying  westward  of  Central  America 
once  touched  the  South  American  continent,  probably  near 


348  OBIGIN   OF   LIFE   IN   AMERICA 

Ecuador  (compare  Fig.  14).  As  this  western  belt  of  land 
was  in  direct  communication  with  the  West  Indies  by  way 
of  Central  America,  it  follows  that  the  West  Indies  and 
Ecuador  were  able  to  enter  into  a  faunistic  exchange.  Many 
instances  might  be  quoted  showing  this  relationship  between 
the  West  Indies,  Central  America  and  western  South 
America,  or  between  parts  of  these  areas.  The  head- 
quarters of  the  snake-like  limbless  amphibians,  known  as 
Coecilia,  are  in  Ecuador.  From  there  they  have  spread 
eastward  through  Guiana  to  Brazil,  and  northward  through 
Colombia  as  far  as  Panama.  No  species  is  actually  known 
to  occur  in  Central  America  beyond  Panama.  I  alluded 
to  the  family  Anguidae  on  several  occasions,  those  generally 
limbless  lizards  to  which  the  so-called  glass -snake  belongs. 
One  genus  with  well -developed  limbs  (Diploglossus),  inhabits 
chiefly  the  principal  islands  of  the  West  Indies,  viz.,  Cuba, 
Haiti  and  Jamaica.  In  Central  America  it  occurs  in  Guate- 
mala and  Costa  Kica,  while  in  South  America  it  inhabits  only 
Ecuador  and  Brazil,  having  apparently  spread  into  the  latter 
state  from  the  west. 

Attention  has  been  drawn  to  the  fact  that  while  the  fauna 
and  flora  of  the  Galapagos  islands  are  principally  Central 
American  and  West  Indian  in  character,  they  also  are  related 
to  those  of  western  South  America.  A  mere  fragment  only 
of  the  animals  and  plants  that  passed  across  the  lands  of 
which  these  islands  formed  part  could  have  been  preserved 
there.  Thus  the  Streptaxidae,  a  family  of  carnivorous  snails 
almost  restricted  in  America  to  the  southern  continent,  do 
not  occur  in  the  Galapagos  islands,  although  a  few  species 
have  penetrated  to  Guatemala,  and  one  even  to  Haiti.  The 
genus  Martinella  is  peculiar  to  Ecuador,  whereas  two  other 
genera,  viz.,  Guestieria  and  Systrophia  appear  to  have  spread 
from  an  Ecuadorian  centre  of  dispersal  to  Peru,  Colombia 
and  Bolivia. 

A  most  interesting  and  important  case  of  discontinuous  dis- 
tribution is  that  of  Clausilia,  a  genus  of  snails  which  I  men- 
tioned when  dealing  with  the  origin  of  the  West  Indian  fauna 
(p.  272).  I  then  stated  the  reasons  for  my  belief  that 
Clausilia  had  travelled  across  the  mid-Atlantic  land  bridge 
from  southern  Europe  to  the  West  Indies  rather  than  by  a 


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ON   THE   ORIGIN   OF   CLAUSILIA  349 

land  connection  between  eastern  Asia  and  Central  America 
as  suggested  by  Dr.  von  Ihering.*  The  American  species 
all  belong  to  the  sub -genus  Nenia,  being  extremely  like  the 
Pyrenean  Clausilia  pauli.  So  far  only  a  single  species  is 
known  from  the  West  Indies,  while  the  genus  has  not 
yet  been  discovered  in  Central  America;  (Fig.  19).  No 
trace  of  Clausilia,  either  recent  or  fossil,  has  been  met  with 
in  North  America  or  in  northern  Asia.  If  we  assume  that 
Clausilia  passed  across  the  Atlantic  Ocean  to  the  West  Indies 
and  thence  to  South  America,  it  should  have  traversed  Central 
America.  It  may  still  be  found  in  Guatemala,  or  it  may 
recently  have  become  extinct.  At  any  rate,  I  think  it  passed 
from.  Central  America  to  the  western  or  Pacific  land  bridge  con- 
necting Guatemala  with  Ecuador.  The  latter  state,  together 
with  northern  Peru,  must  be  looked  upon  as  the  centre  of 
dispersal  of  the  South  American  species  of  Clausilia.  Over 
fifty  Clausilias  are  now  known  from  South  America.f  A  few 
are  found  northward  of  Ecuador  as  far  as  the  province  of 
Bogota  in  Colombia.  The  great  mass,  however,  is  confined  to 
the  highlands  of  Ecuador  and  Peru.  South  of  Bolivia  the 
genus  is  unknown.  Is  there  any  possible  explanation  for  the 
presence  of  this  isolated  colony  of  mountain  snails  in  western 
South  America  except  by  migration  on  a  former  land  connec- 
tion from  Europe  or  eastern  Asia  ?  A  dispersal  of  the  ances- 
tral Clausilia  in  early  Tertiary  times  to  South  America  by 
means  of  either  land  bridge  is  possible,  but  I  greatly  favour 
the  Atlantic  one  (compare  Fig.  14).  It  also  explains  the 
presence  of  a  species  of  Clausilia  in  Portorico  better  than  the 
other  theory. 

Besides  this  instance  of  discontinuous  distribution,  we  more 
over  have  a  large  number  of  others  exhibiting  ancient  rela- 
tionship between  the  faunas  of  the  west  coasts  of  North  and 
South  America.  These  will  be  more  fully  dealt  with  when  we 
come  to  the  consideration  of  the  Chilean  fauna.  I  may  only 
mention  one  example,  that  of  the  three  very  closely  related 
genera  of  scorpions,  Hadrurus,  Hadruroides  and  Caraboc- 
tonus.  The  first  inhabits  California,  having  spread  from  there 

*  Ihering,  H.  von,  "  Verbreitung  der  Heliciden,"  p.  450. 
t  Boettger,  O.,  "Die  Nenia  Arten." 


350  ORIGIN   OF   LIFE   IN   AMERICA 

into  the  adjoining  state  of  Arizona.  The  second  lives  in 
Ecuador  and  Peru.  The  third  is  only  met  with  in  Chile  and 
southern  Peru.  They  all  are  entirely  confined  to  the  west 
coasts.  A  somewhat  more  distant  relationship  exists  between 
the  centipede  Newportia  of  the  West  Indies  and  Central  and 
South  America,  and  Plutonium,  which  is  confined  to  Sardinia 
and  Corsica.  This  affinity  implies  the  presence  of  a  former 
mid-Atlantic  land  bridge  between  the  Mediterranean  and 
Antillean  Eegions  and  between  the  latter  and  northern  South 
America. 

My  principal  aim,  in  alluding  to  the  fauna  of  Ecuador 
and  the  adjoining  areas,  was  to  point  out  the  more  im- 
portant features  of  the  former  as  an  ancient  land-mass 
somewhat  independent  from  the  rest  of  South  America, 
and  the  affinity  of  its  animal  inhabitants  with  those 
of  Central  America,  the  Antilles  and  even  southern 
Europe.  The  antiquity  of  the  region  can  be  demonstrated  by 
many  examples.  Even  birds  show  it  clearly.  Among  one 
hundred  and  eighteen  genera  of  humming-birds  (Troohilidae) 
known  to  science,  Androdon,  Eutoxeres,  Damophila,  Uro- 
chroa,  Phaeolaema,  Agapeta,  lonolaema,  Eugenia  and  others 
are  quite  confined  to  this  region.*  Among  mammals  I  need 
only  mention  the  remarkable  discovery  by  Mr.  Oldfield 
Thomas  f  of  Caenolestes.  This  small  rat-like  mammal  in- 
habits Ecuador  and  the  province  of  Bogota  in  the  adjoining 
State  of  Colombia.  It  is,  therefore,  quite  confined  to  north- 
western South  America.  The  only  other  known  genera  of  the 
family  Epanorthidae  were  found  in  the  Santa  Cruz  deposits 
of  Argentina.  The  presence  of  a  still  living  member  of  this 
otherwise  extinct  family  is  of  considerable  interest.  Even 
more  important  is  the  fact  that  Caenolestes  is  the  only  living 
American  herbivorous  marsupial  mammal  more  nearly  related 
to  the  kangaroo  of  Australia  than  to  the  American  representa- 
tives of  the  order — the  opossums. 

The  only  South  American  representative  of  the  family  of 
bears  (Ursidae)  known  as  the  spectacled  bear  (Tremarctos 
ornatus),  on  account  of  the  yellow  rings  surrounding  its  eyes, 

*  Hartert,  E.,  "  Trochilidae." 
t  Thomas,  O.,  "  On  Caenolestes,'1 


THE   BEAK  OF   SOUTH   AMERICA  351 

is  confined  to  the  Andes  between  Colombia  and  Chile,  that  is 
to  say,  altogether  to  western  South  America.  This  range  sug- 
gests that  the  bears  are  not  originally  a  South  American  family, 
otherwise  we  might  expect  their  having  a  wider  distribution. 
The  only  alternative  is  that  they  migrated  from  some  other 
part  of  the  world  to  the  part  of  South  America  where  they 
still  maintain  themselves.  Dr.  von  Ihering  *  argued  that  the 
ancestors  of  the  South  American  bear  originally  came  from 
Asia,  and  that  they  wandered  across  on  a  Miocene  land  con- 
nection which  united  eastern  Asia  with  Central  America  with- 
out touching  North  America.  In  that  case  they  would  be  older 
than  the  North  American  bears  which,  according  to  Professor 
Osborn,!  belong  to  the  much  later  Pleistocene  Eurasiatic  inva- 
sion. As  a  matter  of  fact,  the  geological  history  of  the  bears  in 
America  has  never  received  the  careful  attention  it  deserves. 
Bears,  it  is  well  known,  are  entirely  absent  from  Africa  south 
of  the  Sahara,  that  is  to  say,  from  what  is  known  as  the 
Ethiopian  Region,  and  no  fossil  remains  of  any  members  of 
the  family  have  ever  been  discovered  there.  Hence  it  is  un- 
likely that  Africa  was  the  source  of  the  Ursidae  or  that  they 
invaded  South  America  by  means  of  a  direct  land  bridge  from 
that  continent  as  suggested  by  Dr.  Ameghino.  J  The  absence 
of  bears  from  the  whole  of  eastern  South  America  indicates, 
moreover,,  that  bears  have  made  their;  entry  from  the  west.  Thte 
bears  of  South  and  North  America  are  not  closely  related. 
They  appertain  to  different  genera.  A  fossil  bear  (Arcto- 
therium  vetustus),  belonging  to  a  genus  closely  related  to  or 
identical  with  Tremarctos,  has  been  recorded  by  Dr.  Ameghino 
from  the  Entrerios  deposits  of  Argentina  which  are  of  Mio- 
cene age.  It  would  appear  on  that  account  as  if  Dr.  von 
Ihering's  suggestion  that  the  South  American  bears  were  older 
than  the  North  American  ones,  and  had  quite  an  independent 
Asiatic  origin,  was  borne  out  by  palaeontological  evidence. 
Since  Arctotherium  also  occurs  fossil  in  some  Pleistocene 
beds  of  North  America  it  must  have  spread  northward  in 
recent  times  and  subsequently  have  become  extinct  there. 

*  Ihering,  H.  von,  "  Greschichte  der  Siidamer.  Raubtiere,"  p.  1*79. 

t  Osborn,  H.  F.,  "Age  of  Mammals,"  p.  438. 

J  Ameghino,  Fl.,  "  Tetraprothomo  argentinus,"  p.  230. 


352  ORIGIN   OF   LIFE   IN   AMERICA    . 

Among  living  bears  the  nearest  relation  of  the  Andean  species 
seems  to  be  the  Malayan  bear  (Ursus  malayanus)  inhabiting 
the  Malay  peninsula  and  neighbouring  countries.     But  the 
European  Miocene  Ursus  boeckhi  and  the  Pliocene  Ursus 
etruscus  are  members  of  the  same  group,  and  it  appears  to  me 
possible  that  the  South  American  Tremarctos  and  the  Ursus 
malayanus  groups  may  have  had  a  common  ancestor  which 
passed  from  southern  Europe  to  South  America  by  way  of  the 
mid-Atlantic  land  bridge  and  the  Antilles  in  Oligocene  times. 
Although  tapirs  have  a  much  wider  range  in  South  America 
than  bears,  their  American  distribution  also  suggests  that, 
like  the  bears,  they  are  immigrants  either  from  Europe  or 
Asia.     Their  general  range  is  in  so  far  comparable  to  the 
distribution  just  cited  as  the  only  living  tapirs  are  confined 
to  South  America  and  southern  Asia.  Tapirs  are  often  alluded 
to  as  among  the  most  striking  and  familar  instances  of  what 
is  called  "  discontinuous  distribution."   But  we  know  a  good 
deal  more  of  the  geological  history  of  tapirs  than  of  bears.  Of 
the  two  South  American  tapirs  the  smaller  one  is  confined  to 
the   Andes   between   Colombia   and   Peru,    while   the  other 
(Tapirus  americanus)  has  probably  spread  eastward  from  a 
western  centre  of  dispersal,  for  it  occurs  from  eastern  Peru  to 
Brazil,  Venezuela,  Guiana  and  to  northern  Argentina.    Two 
other  tapirs  live  in  Central  America.   The  genus  is  only  known 
fossil  from  Pleistocene  South  American  deposits,  and  it  might 
appear  as  if  it  were  a  recent  immigrant  from  North  America. 
But   in   the   latter   continent   only   a    single   fossil   species 
(Tapirus  haysi)   has  been  discovered,  and  that  likewise  in 
Pleistocene  beds.    Professor  Osborn  asserts  that  a  tapir,  un- 
distinguishable    from    the    living    South    American    species 
(Tapirus  americanus),  invaded  North  America  together  with 
Mylodon  and  Megatherium  in  Pleistocene  times.     I  am  not 
aware  of  any  reliable  osteological  characters  distinguishing  the 
living  South  and  Central  American  species.  If  there  are  such, 
Professor  Osborn's  *  statement  may  possibly  refer  to  one  of 
the  latter.     Still,  it  is  quite  evident  that  the  genus  Tapirus 
could  not  have  come  across  any  Bering  Strait  land  connection 
in  Pleistocene  times  and  have  travelled  to  Argentina  before 

*  Osborn,  H.  F.,  "Age  of  Mammals,"  p.  472. 


THE    TAPIRS   OF    SOUTH   AMERICA  353 

the  end  of  the  Pleistocene  Period,  nor  does  Professor  Osborn 
suggest  such  a  mode  of  origin.  The  problem,  therefore,  still 
remains  unsolved.  Mr.  Earle  *  pointed  out  that  tapir-like 
creatures  or  tapiroids  arose  about  the  same  time  in  Europe 
and  North  America.  In  the  light  of  more  recent  researches 
it  would  appear  that  the  Eocene  Systemodon  and  Isectolophus 
are  confined  to  North  America,  while  the  European  tapiroid 
remains  belong  to  the  related  family  Lophiodontidae.  The 
true  tapirs,  to  which  the  American  genera  belong,  do  not 
make  their  appearance  in  Europe  until  the  Oligocene  Period.- 
According  to  Professor  Osborn,f  the  existing  Malayan 
tapir  is  almost  identical  with  the  Pliocene  tapir  of  southern 
Europe  (T.  arvernensis),  and  I  cannot  help  thinking  that  the 
genus  Tapirus  has  evolved  in  the  Mediterranean  region  from 
American  ancestors  much  earlier  than  is  generally  supposed, 
the  modern  tapirs  having  spread  west  and  east  from  this  centre 
of  dispersal  at  a  time  when  the  mid-Atlantic  land  bridge  was 
still  in  existence. 

If  we  pass  from  Ecuador  southward  along  the  chain  of  the 
Andes,  we  meet  with  a  number  of  new  forms  of  animal  life, 
all  of  which  are  more  or  less  confined  to  this  great  mountain 
range.  In  certain  districts  in  Peru  at  high  altitudes  there 
are  immense  colonies  of  curious  little  squirrel-like  rodents 
with  very  large  ears  and  grey  fur  of  extreme  softness.  Like 
the  prairie-dogs  and  other  North  American  rodents,  these 
chinchillas,  as  they  are  called,  live  in  burrows.  There  is  a 
larger  kind,  too,  which  has  still  longer  ears  and  great  black 
whiskers,  differing  sufficiently  from  Chinchilla  to  deserve 
recognition  as  the  distinct  genus  Lagidium.  Both  genera 
inhabit  exclusively  the  high  mountains  between  Peru  and 
Chile.  A  third  member  of  the  same  tribe,  the  viscacha,  lives  on 
the  plains  of  Argentina,  and  will  be  more  fully  described  later 
on.  These  three  genera  included  in  the  family  Viscaciidae 
(Lagostomidae)  have,  to  judge  from  their  distribution,  pro- 
bably originated  from  one  or  more  western  ancestors.  But 
Dr.  Ameghino  J  has  described  quite  a  number  of  genera 

*  Earle,  C.,  "Fossil  Mammalia  of  Europe,"  p.  115. 

t  Osborn,  H.  F.,  "Age  of  Mammals,"  p.  315. 

J  Ameghino,  Fl.,  "  Formations  sedimentaires,"  p.  428. 

L.A.  A  A 


354  ORIGIN   OF    LIFE   IN    AMERICA 

obviously  of  the  same  family  from  the  Patagonian  and  Argen- 
tine Eocene,  Oligocene,  Miocene  and  Pliocene  beds,  so  that 
it  would  seem,  as  he  indeed  suggests,  as  if  South  America 
had  been  the  original  home  of  the  family.  Professor  Schlosser 
quite  agrees  that  these  are  the  undoubted  ancestors  of  the  still 
existing  South  American  genera,  but  he  thinks  that  Dr. 
Ameghino  is  mistaken  about  the  age  of  the  South  American 
deposits  in  which  these  rodents  occur.  He  believes  them  to 
be  not  earlier  than  Miocene,  while  more  primitive  ancestors 
of  these  rodents  are  to  be  found  in  European  Oligocene  beds. 
The  Theridomyidae  of  Europe  which,  according  to  Professor 
Schlosser,  have  given  rise  'to  Chinchilla  and  its  relatives,  are 
more  primitive  in  structure  than  the  latter  and  nearly  allied 
to  them.  The  same  writer  acknowledges  that  other  groups  of 
mammals  also  entered  South  America  from  Europe,  although 
he  does  not  give  us  the  least  clue  as  to  the  means  they  em- 
ployed in  doing  so.  Whether  Chinchilla  and  its  relations  are 
descended  from  European  ancestors,  or  whether  the  European 
Theridomyidae  have  been  derived  from  South  America,  is 
really  comparatively  immaterial  to  our  present  enquiries.  The 
important  point  at  issue  is  the  recognition,  by  such  an  autho- 
rity as  Professor  Schlosser,*  that  the  two  continents  have  had 
a  faunistic  interchange  about  Oligocene  times  in  which  North 
America  took  no  part. 

Ecuador  possesses  such  a  number  of  quaint  archaic  forms 
of  animal  life  that  I  have  scarcely  been  able  to  give  a  general 
sketch  even  of  the  main  features  of  the  fauna,  but  before 
dealing  with  the  causes  that  produced  them  I  must  mention 
one  more  instance.  It  is  the  most  noteworthy  perhaps  of  the 
whole  deer-tribe,  namely,  the  little  pudu  (Pudua  mephisto- 
pheles).  No  larger  than  a  hare,  this  tiny  creature,  with  its 
simple  unbranched  spike-antlers,  reminds  us  of  some  of  the 
early  progenitors  of  the  deer-tribe.  The  genus  Pudua  has  two 
species,  both  entirely  confined  to  western  South  America,  like 
the  bear  and  Chinchilla.  One  of  these  lives  in  the  mountains 
of  Ecuador,  the  other  in  Chile  and  on  the  island  of  Chiloe. 
I  need  not  repeat  the  remarks  made  in  an  earlier  chapter 

*  Schlosser,  M.,  "Tullberg's  System  der  Nagethiere,"  pp.  741— 
742. 


DWAKF   DEER  OF    SOUTH   AMERICA          355 

(pp.  107—112),  when  I  argued  that  the  South  American 
deer  had  not  originated  in  North  America,  as  is  generally 
assumed,  but  in  South  America  from  European  ancestors. 

I  venture  to  think  that  most  palaeontologists  will  agree  with 
my  contention,  which  is  by  no  means  a  new  one,  that  there  is 
quite  a  remarkable  affinity  between  the  living  western  South 
American  groups  of  mammals  and  those  of  the  early  European 
Tertiaries.  It  is  my  interpretation  of  the  causes  which  pro- 
duced this  striking  feature  that  will  not  so  readily  commend 
itself.  The  faunas  of  the  West  Indies  and  Central  America 
form  the  chief  difficulty  to  the  acceptance  of  my  theory.  I 
acknowledge  that  comparatively  few  traces  remain  in  these 
countries  of  the  vast  migration  that  swept  across  them.  In 
the  West  Indies,  I  presume,  the  subsequent  submergence  must 
have  destroyed  the  principal  part  of  the  original  fauna,  while 
Central  America  in  its  present  form  did  not  exist  at  the  time 
when  the  mid-Atlantic  land  bridge  spanned  the  ocean.  Com- 
petition with  newer  arrivals,  moreover,  must  have  been  very 
keen,  so  that  Central  America  became  unfitted  for  the  survival 
of  European  relict  forms.  This  explanation  does  not  appear 
altogether  satisfactory.  But  the  crux  of  the  problem  is  North 
America.  By  what  possible  system  of  land  bridges  can 
western  South  America  have  received  part  of  its  fauna  from 
Europe  and  have  exchanged  certain  groups  in  return  without 
North  America  having  become  affected  ?  This  seems  all  the 
more  puzzling  considering  that  I  drew  special  attention  in 
Chapter  IX.  to  the  conspicuous  faunistic  relationship  between 
southern  Europe  and  California.  The  faunas  of  western 
North  America  and  western  South  America  as  a  whole  are 
strikingly  different,  and  yet  I  have  indicated  certain  points 
of  resemblance,  especially  between  some  of  the  more  ancient 
members  of  the  two  faunas.  If  we  supposed  the  mid- 
Atlantic  land  bridge  of  early  Tertiary  times  to  have  been 
connected  at  first  with  both  western  North  America  and 
western  South  America,  while  disconnected  at  all  other  points 
with  these  continents,  certain  very  ancient  points  of  resem- 
blance between  the  two  continents  and  with  Europe  might 
thus  receive  a  satisfactory  explanation.  If  the  same  land 
bridge  had  then  become  entirely  separated  from  North 
America,  remaining  united  with  South  America,  the  faunistic 

A  A  2 


356  ORIGIN   OF   LIFE   IN   AMERICA 

interchange  would  have  continued  only  between  Europe  and 
South  America.  If  the  land  bridge  had  then  become  discon- 
nected with  South  America,  and  joined  to  western  North 
America,  while  the  Antilles  were  submerged,  the  latest  Euro- 
pean emigrants  would  have  taken  refuge  in  California  as  the 
last  remnants  of  the  old  land  sank  into  the  Pacific.  That 
something  of  this  kind  actually  took  place  I  feel  convinced, 
although  the  details  of  these  events  must  be  founded  largely 
on  geological  studies  which  unfortunately  are  as  yet  insuffi- 
ciently known.  My  own  knowledge,  moreover,  of  the  geo- 
logical features  of  the  regions  alluded  to  is  only  fragmentary. 
Nevertheless,  the  little  I  have  been  able  to  gather  does  not 
tend  to  contradict  the  general  scheme  of  the  theories  I  now 
suggest. 

In  later  Cretaceous  times  a  broad  sea,  as  I  have  pointed 
out  on  several  occasions,  separated  western  from  eastern  North 
America,  while  the  Pacific  Ocean  flooded  a  large  portion 
of  the  western  States,  so  as  to  leave  only  a  comparatively 
narrow  strip  of  land  between  the  two  seas.  The  Cretaceous 
deposits  can  be  traced  all  along  the  Pacific  coast  as  far  almost 
as  the  extreme  tip  of  Lower  California.  Here  they  suddenly 
stop.  The  Cretaceous  sea  evidently  did  not  cover  the  in- 
teresting Cape  Region  of  Lower  California  nor  any  part  of 
western  Mexico.  There  are  reasons  for  the  belief  that  even 
at  this  time  the  western  part  of  the  coast  ranges  of  California 
were  not  submerged,  thus  suggesting  the  existence  of  another 
land-mass  to  the  west  of  the  Californian  Sea.  This  land  may 
have  been  connected  with  the  Cape  Region  of  Lower  Cali- 
fornia, and  thus  with  Mexico.  By  the  end  of  Cretaceous  time, 
says  Professor  Smith,*  the  subsidence  and  erosion  of  the 
western  part  of  the  continent  had  almost  established  a  con- 
nection between  the  Pacific  Gulfs  in  California  and  Oregon 
and  the  old  Mediterranean  Sea  in  the  Mississippi  valley.  The 
intervening  isthmus  was  covered  by  extensive  marshes.  Pro- 
fessor Smith  tells  us  that  the  geographical  conditions  re- 
mained the  same  in  Eocene  times  as  in  the  Upper  Cretaceous, 
except  that  the  sea  encroached  still  further  on  the  land.  Now 
it  is  precisely  at  this  time  that  we  notice  a  striking  affinity 

*  Smith,  J.  Perrin,  "  Geological  History  of  California,"  pp.  347—348. 


ANCIENT  LAND  BRIDGES  357 

between  the  western  mam'malian  fauna  of  North  America  and 
those  of  Europe  on  the  one  hand  and  South  America  on  the 
other.  Since  south-western  North  America  was  then  prac- 
tically isolated  and  separated  from  the  remainder  of  North 
America  by  great  ocean  belts,  how  can  we  imagine  these  Euro- 
pean and  South  American  affinities  to  have  been  brought 
about  ?  Surely  only  by  some  land  connection  that  lay  to  the 
south.  I  suggest  that  it  was  from  western  Mexico  that  these 
earliest  mammals  invaded  south-western  North  America. 
Then  followed  a  time  when  the  Gulf  of  Mexico  and  the  Pacific 
Ocean  probably  communicated  with  one  another,  thus  separat- 
ing the  supposed  mid-Atlantic  land  bridge  from  North 
America.  Professor  Smith  speaks  only  of  a  temporary  con- 
nection between  the  oceans,  accounted  for  by  the  occurrence 
in  Oregon,  as  well  as  in  California.,  of  the  Atlantic  marine 
mollusk  Venericardia  planicosta.  Before  the  Miocene  Period 
this  Atlantic  connection  had  ceased,  and  the  faunas  of  the 
later  Tertiary  were  wholly  of  the  Pacific  type,  continues  Pro- 
fessor Smith.*  He  does  not  allude  to  Oligocene  deposits,  but 
it  is  not  long  since  that  these  were  recognised  at  all  outside 
Europe.  At  any  rate,  after  the  Eocene  follows  a  time  during 
which  the  Pacific  recedes  from  the  wes.t  coast,  thus  giving 
full  opportunities  for  an  invasion  of  animals  from  the  theo- 
retical western  land.  We  may  suppose  that  this  corresponded 
with  the  Oligocene  Period  and  with  the  time  when,  as  Pro- 
fessor Osborn  tells  us,  there  was  a  re-establishment  of  the 
faunal  resemblance  of  south-western  North  America  with 
Europe.  Possibly  Chile,  which  was  connected  at  an  earlier 
period  with  this  same  western  belt  of  land,  became  separated 
from  it.  This  again  was  succeeded  by  a  period  of  marine 
transgression  in  the  west.  Even  northern  Mexico  was  largely 
covered  by  the  sea,  as  well  as  both  sides  of  Lower  California 
and  a  large  portion  of  western  California.  All  this  time 
western  South  America  must  have  risen  gradually  above  the 
sea,  and  I  presume  that  certain  fragments  of  land,  like 
Peru,  became  joined  to  the  long  peninsula  which  stretched 
far  southward  running  parallel  with  the  newly  formed  west 
coast  of  South  America.  Thus  while  North  America  no  longer 

*  Smith,  J.  Perrin,  "  Geological  History  of  California,"  p.  348. 


858  ORIGIN   OF   LIFE  IN   AMERICA 

received  its  quota  of  European  emigrants,  they  found  suitable 
accommodation  on  the  newly-formed  land  of  north-western 
South  America.  The  mid- At]  an  tic  land  bridge  now  ceased 
to  exist,  and  far-reaching  geographical  changes  super- 
vejied  almost  everywhere.  Owing  possibly  to  the  extensive 
subsidences  in  the  Pacific  Ocean,  the  land  that  I  assume  to 
have  occupied  part  of  the  eastern  Pacific,  was  gradually  re- 
duced in  size.  But,  being  no  longer  tenanted  by  the  more 
vigorous  and  more  advanced  European  types,  South  American 
forms  now  commenced  to  occupy  this  land,  thus  first  reaching 
the  Antilles  and  then  North  America  as  it  again  became  fully 
connected  with  the  western  land.  Central  America  in  its  pre- 
sent shape  had  not  yet  come  into  existence.  Not  long  ago  it 
was  thought  that  the  Central  American  isthmus  must  have 
been  first  utilised  as  a  highway  at  the  beginning  of  the  Plio- 
cene Period,  and  that  then  the  great  edentates  began  to  pour 
into  North  America.  Now  the  surprising  evidence  has  come 
to  hand  that  true  edentates  of  the  Megalonyx  type  occur  in  the 
Middle  Miocene  Mascall  beds  of  Oregon.  Dr.  Matthew  writes 
to  inform  me  that  the  Megalonyx  remains  only  doubtfully 
belong  to  this  horizon.  Professor  Osborn,*  on  the  other  hand, 
believes  in  the  discovery,  and  expresses  the  opinion  that  it 
tells  in  favour  of  my  theory  of  the  former  existence  of  a 
western  land  connecting  North  and  South  America  inde- 
pendently of  Central  America.  Still,  he  points  out  that  it  is 
inconsistent  with  the  fact  that  other  animals  did  not  pass 
south  or  north. 

Let  us  examine  some  of  the  other  new  arrivals  in  North 
America  in  Miocene  times,  and  endeavour  to  trace  their  geo- 
logical history.  One  of  the  most  noteworthy  of  these  is  the 
first  appearance  in  North  America  of  elephants  (Mastodon). 
Since  Dr.  Andrews'  f  surprising  discoveries  in  northern 
Africa  were  published,  Africa  is  generally  looked  upon  as  the 
original  home  of  elephants,  the  earliest  form  being  Moeri- 
therium,  from  which  later  on  Palaeomastodon  and  its  more 
modern  relations  arose.  The  first  of  the  latter  was  the  Mas- 

*  Osborn,  H.  P.,  "Age  of  Mammals,"  pp.  289—292. 
t  Andrews,  C.  W.,  "Tertiary  Vertebrates  of  the  Fayum,"  pp.  xvi— 
xviii. 


FOSSIL   ELEPHANTS   IN   AMEEICA  359 

todon  called  Trilophodon  on  account  of  the  three  transverse 
rows  of  cusps  on  its  intermediate  grinding  teeth.  Now  Trilo- 
phodon arrived  in  Europe  and  in  North  America  at  about  the 
same  time  during  the  Miocene  Period.  Professor  Osborn 
assumes  that  these  mammals  came  from  Asia,  although  we 
possess  no  evidence  of  their  having  reached  the  northern  or 
eastern  parts  of  that  continent.  We  might  be  tempted  to 
invoke  a  direct  land  connection  between  Africa  and  South 
America  in  Oligocene  times,  but,  as  we  shall  see  later  on,  that 
connection  must  have  disappeared  at  a  still  earlier  period. 
However,  these  and  other  problems  will  be  considered  in  the 
next  chapter. 

Several  important  zoogeographical  features  of  western  and 
northern  South  America  still  remain  to  be  considered.  Special 
researches  among  the  Cretaceous  rocks  and  their  fossils  in 
Peru  have  shown  that  during  Lower  Cretaceous  time,  that  is  to 
say,  towards  the  latter  part  of  the  Mesozoic  Era,  the  greater 
part  of  the  country  was  buried  deeply  beneath  the  ocean. 
From  Bolivia  and  Chile,  even  as  far  south  as  the  Strait  of 
Magellan,  Lower  Cretaceous  deposits  have  been  discovered. 
North  of  Peru  they  occur  in  Colombia  and  Venezuela.  The 
most  surprising  circumstance  connected  with  these  South 
American  beds,  however,  is  the  great  number  of  species  that 
are  either  identical  with  or  closely  allied  to,  such  as  occur  iq 
the  Cretaceous  deposits  of  north  Africa,  the  south  of  France, 
Switzerland  and  the  neighbouring  countries.*  More  than 
sixty  years  ago  D'Orbigny  already  drew  attention  to  this  fact, 
and  argued  from  it  that  a  land  connection  across  the  mid- 
Atlantic  must  have  enabled  species  to  cross  the  ocean  by 
travelling  along  a  continuous  shore-line.  On  the  other  hand, 
scarcely  any  affinity  exists  between  the  Cretaceous  of  Vene- 
zuela and  that  of  Mexico  or  Texas,  thus  clearly  implying  the 
presence  of  a  land  barrier  between  these  two  areas.  The  old 
highland  of  Guiana  east  of  Venezuela  was  long  ago  a  penin- 
sula of  the  archaean  highlands  of  Brazil  in  the  south.  There 
is  reason  to  believe  that  the  great  mountain  chain  of  the 
Andes  gradually  emerged  out  of  this  sea.  During  this  process 
some  of  the  newly-formed  islands  probably  became  attached 

*  Paulcke,  W.,  "  Kreideformation  in  Sudamerika,"  pp.  305— 308. 


360  ORIGIN   OF   LIFE   IN   AMERICA 

to  parts  of  pre-existing  western  lands.     All  through  Tertiary 
time  the  mountains  must  have  continued  to  rise,  though  our 
knowledge  of  later  geological  history  is  still  meagre.    We  know 
that  Tertiary  marine  deposits  occur  in  the  Orinoco  valley,  and 
it  is  likely  that  a  narrow  marine  channel  still  separated  north- 
western South  America  from  the  rest  of  the  continent  during 
the  earlier  part  of  the  Tertiary  Era.     The  Amazon  valley  no 
doubt  was  at  that  time  a  hay  of  the  Pacific  ;  still,  I  am  unaware 
of  any  geological  or  zoogeographical  evidence  for  Professor 
Osborn's  supposition  that  north  and  middle  South  America 
were  completely  divided  in  Miocene  times  by  a  wide  sea.    That 
the  Orinoco  and  Amazon  valleys  were  in  communication  with 
one  another  for  a  long  time  is  shown  by  the  fact  that  one  of 
the  species  of  manatees  (Trichechus  inunguis)  and  the  fresh- 
water turtle  Podocnemis  expansa  are  confined  to  the  upper 
portions    of   these   two    great    rivers.      A    most    surprising 
confirmation  of  the  theory  that  an  ocean  bay  extended  to  the 
neighbourhood  of  the  Andes  has  been  discovered  near  the  small 
town  of  Pebas,  on  the  upper  Maranon,  more  than  twenty 
degrees  of  longitude  west  of  the  mouth  of  the  Amazon.    Pro- 
fessor Boettger  described  deposits  from  this  locality  contain- 
ing typically  brackish  water  mollusks  which  could  only  have 
lived  in  the  neighbourhood  of  the  sea.    He  naturally  came  to 
the  conclusion  that  the  Atlantic  then  had  invaded  the  Amazon 
valley  so  as  to  extend  near  to  the  foot  of  the  Andes.     But 
Dr.  Katzer's  view,  already  alluded  to,  according  to  which  the 
Amazon  drainage  only  changed  eastward  in  later  Tertiary 
times,  appears  to  me  to  agree  better  with  the  zoogeographical 
features  of   eastern   South  America.     Professor  Boettger  * 
looked  upon  the  Pebas  beds  as  being  of  Oligocene,  possibly 
Eocene  age.    The  fresh-water  fish  fauna  of  the  Pacific  slopes 
of  southern  Ecuador  still  exhibits  such  affinity  to  that  of  the 
Amazon  that  the  Ecuador  mountains  could  only  have  had  a 
slight  elevation  until  comparatively  recent  geological  times. 
Hence  we  may  assume  that  the  Pacific  extended  to  the  neigh- 
bourhood of  Pebas  when  thes;e  brackish  water  beds  were  laid 
down. 

An    interesting    zoogeographical    demonstration    of    the 

*  Boettger,  0.,  "  Die  Tertiarfauna  von  Pebas,"  p.  503. 


HISTOKY  OF  EIVER  AMAZON  361 

gradual  elevation  and  consequent  slow  change  of  the  marine 
character  of  an  ancient  lagoon  is  afforded  by  Lake  Titicaca 
on  the  borders  of  Peru.  This  lake,  with  a  length  of  eighty 
miles,  lies  in  a  mountain  valley  over  12,000  feet  above  sea- 
level,  and  occupied  not  long  ago  a  much  larger  area.  To  sup- 
pose that  this  region  should  have  risen  from  sea-level  to  such  a 
height,  and  still  preserve  the  remnants  of  an  ancient  marine 
fauna  dating  back  to  the  period  when  it  was  a  gulf  of  the 
Pacific,  would  seem  a  very  bold  theory.  Professor  Suess,* 
indeed,  expresses  the  opinion  that  the  presence  of  a  marine 
fauna  in  Lake  Titicaca  cannot  be  regarded  as  a  sufficient  proof 
of  the  theory  that  the  lake  was  at  sea -level  within  recent 
geological  times.  I  quite  concur  with  Professor  Suess  in  so 
far  as  the  assumption  of  a  recent  elevation  is  concerned,  but 
we  have  reason  to  believe  that  certain  ancient  forms  of  animal 
life,  particularly  among  aquatic  groups,  have  transmitted 
their  specific  characters  unchanged  to  their  modern  descen- 
dants. It  is  conceivable,  therefore,  and  even  possible,  that  the 
striking  affinity  of  the  fauna  of  Lake  Titicaca  to  that  of  the 
Pacific  coast  may  have  been  preserved,  although  the  actual 
junction  of  the  lake  with  the  sea  took  place  perhaps  as  far  back 
as  early  Tertiary  times.  The  theory  of  the  recent  elevation  was 
first  mooted  by  Mr.  A.  Agassiz,f  owing  to  the  discovery  in  the 
lake  of  eight  species  of  the  marine  amphipod  Allorchestes,  one 
of  which  (A.  dentatus)  differs  but  slightly  from  a  form  still 
inhabiting  the  Strait  of  Magellan.  That  fact  alone  might 
be  attributable  to  accidental  dispersal,  although  the  enormous 
difference  in  height  between  the  sea  and  the  lake,  and  the 
circumstance  of  there  being  eight  different  species  of  Allor- 
chestes, would  be  difficult  to  explain  on  that  theory.  But 
besides  this  marine  crustacean  other  members  of  a  marine 
fauna  have  been  shown  to  exist  in  Lake  Titicaca,  and  thus 
the  case  against  accidental  dispersal  has  assumed  a  stronger 
position.  The  fish  fauna  consists  of  a  catfish  (Pigidium 
rivulaturri),  belonging  to  a  genus  which  is  very  widely  distri- 
buted all  over  South  America,  and  several  species  of  Orestias. 
The  latter  genus  is  quite  confined  to  Lake  Titicaca,  and  since 

*  Suess,  E.,  "  Antlitz  der  Erde,"  I.,  p.  693. 
t  Agassiz,  A.,  "  Lake  Titicaca,"  p.  287. 


362  OBIGIN  OF  LIFE  IN   AMERICA 

its  nearest  relations  are  all  marine  forms,  its  ancestors,  as 
Professor  Eigenmann  *  remarks,  could  only  have  entered  the 
area  when  it  was  still  a  gulf  of  the  sea. 

In  the  Eocene  Period  "  Archiguiana,"  as  Dr.  von  Ihering 
named  the  ancient  highland  of  Guiana  and  eastern  Venezuela, 
was  supposed  by  this  writer  to  have  been  isolated  from  the 
highland  of  Brazil.  And,  indeed,  the  mountain  plateau  of 
Guiana  contains  a  very  large  number  of  archaic  and  most 
peculiar  types,  some  of  which  seem  to  spread  westward  into 
Venezuela  and  Colombia  rather  than  into  Brazil.  Yet  the 
great  majority  of  these  ancient  forms  of  Guiana  also  occur 
southward  in  eastern  Brazil.  One  of  the  most  noteworthy 
birds,  the  hoatzin  (Opisthocomus  hoatzin),  whose  young 
climb  about  among  the  branches  of  the  trees  by  means  of 
well -developed  claws  on  their  wings,  and  which  have  been 
placed  into  a  distinct  order  by  themselves,  range  southward 
as  far  as  Bolivia.  The  chatterers  (Cotingidae)  comprising 
some  of  the  most  ornate  and  peculiar  birds  of  South  America, 
are  almost  equally  divided  between  Brazil  and  Guiana.  The 
familiar  umbrella  bird  (Cephalopterus  ornatus),  the  bell  bird 
(Casmorhynchus  niveus),  the  bald-headed  crow  (Gymnoce- 
phalus  calvus),  and  the  cock-of-the-rock  (Rupicola  crocea),  all 
belong  to  genera  which  have  spread  westward  from  Guiana 
rather  than  into  Brazil.  In  all  these  cases  we  have  to  deter- 
mine what  was  the  original  centre  of  dispersal.  The  singular 
genus  of  snails  Ampullaria  probably  spread  across  South 
America  from  a  Brazilian  centre,  and  so  did  the  fresh -water 
crab  (Pseudothelphusa)  and  the  whole  family  of  fishes  called 
Cichlidae.  The  snail  Strophocheilus,  the  fresh-water  mussel 
Unio,  the  archaic  arthropod  Peripatus,  the  family  of  tortoises 
Cinosternidae  and  others,  have  apparently  entered  Brazil  from 
the  north  and  west.  As  I  shall  endeavour  to  show  in  the  next 
chapter,  many  of  the  forms  that  have  spread  from  the  Brazi- 
lian highlands  have  near  relations  in  Africa,  while  among  the 
northern  and  western  immigrants  into  Brazil  scarcely  any 
have  succeeded  in  crossing  the  Atlantic  area  to  Africa. 

*  Eigenmann,  C.  H.,  "  Freshwater  Fishes  of  South  America,"  p.  521. 


CHAPTEK  XIV 

EASTERN    SOUTH    AMERICA 

WHEN  we  consider  that  Brazil  covers  an  area  larger  than 
that  of  the  whole  of  Europe,  merely  the  roughest  outlines  of 
the  general  zoological  features  of  that  vast  country  can  be 
attempted  in  a  work  of  this  nature.  The  highlands  of  Brazil, 
as  I  have  mentioned  already,  are  confined  to  the  east,  being 
surrounded  by  the  ocean  on  one  side  and  by  a  continuous 
tract  of  lowlands  on  the  others.  It  is  believed  that  the 
mountains  were  once  continuous  with  those  of  Guiana 
right  across  the  present  mouth  of  the  river  Amazon. 
The  whole  of  the  area  between  the  two  great  highlands 
of  Brazil  and  Guiana  is  drained  by  the  mighty  Amazon, 
whose  waters  exceed  in  quantity  that  of  any  river  in  the  world. 
The  Paraguay  and  its  tributary  the  Parana  drain  the  south- 
western parts  of  Brazil.  Practically  the  whole  of  the  country 
lies  in  the  tropics.  The  combined  influence  of  high  tempera- 
ture and  abundance  of  moisture  thus  produces  that  exuber- 
ance of  animal  and  plant  life  which  is  so  characteristic  of 
Brazil.  The  great  tropical  forests  are  truly  bewildering  in  the 
wealth  and  variety  of  their  vegetation,  and  it  is  here  that  we 
realize  more  than  anywhere  else  the  keen  struggle  for  exist- 
ence as  applied  to  plants  and  animals.  In  their  constant  efforts 
to  reach  the  light,  and  in  their  endeavour  to  obtain  a  full  share 
of  it,  the  trees  crowd  and  press  upon  one  another  until  the 
weaker  succumb.  In  their  turn  they  are  invaded  again  by 
others,  while  hosts  of  enemies,  parasitic  plants  and  climbers, 
twine  round  and  strangle  the  less  sturdy  long  before  they 
succeed  in  attaining  their  object.  We  are  thus  presented  with 
a  scene  of  savage  warfare  among  plants.  It  is  less  evident 
among  animals.  But  the  ringing  sound  of  the  multitude  of 
voices  issuing  out  of  the  forest  reminds  the  traveller  that  in 
this  teeming  profusion  of  nature  there  must  be  an  acute 


364  ORIGIN   OF   LIFE   IN   AMERICA 

struggle  for  life  among  animals  as  well  as  among  plants. 
And  yet,  except  birds,  insects  and  lizards,  animals  do 
not  appear  to  be  present  in  unusually  large  numbers.  The 
large  class  of  mammals,  which  elsewhere  form  such  a  con- 
spicuous feature  of  a  fauna,  seem  almost  to  be  absent.  This 
is  largely  due  to  the  fact  that  Brazil  is  really  poor  in  terrestrial 
mammals.  Those  that  do  inhabit  the  country  are  chiefly  of 
arboreal  habits,  and  thus  escape  attention.  Mr.  Bates  * 
believes  that  the  South  American  fauna  has  been  slowly 
adapted  to  an  arboreal  life,  and  that  extensive  forests 
must  always  have  existed  since  the  region  was  first  peopled 
by  mammalia. 

Among  these  arboreal  mammals  the  family  of  the  capuchin 
monkeys  (Cebidae),  whose  unusually  prehensile  tail  gives 
them  peculiar  facilities  for  climbing,  are  the  most  noteworthy. 
They  range  all  over  tropical  America,  being  most  abundant 
in  the  dense  forest  regions  of  Brazil.  In  some  monkeys,  like 
the  howlers  (Mycetes),  the  end  of  the  tail  underneath  is  devoid 
of  hair,  and  thus  acts  with  even  greater  efficiency  than  in 
capuchins  (Cebus).  The  sakis  (Pithecia)  and  squirrel-mon- 
keys .(Chrysothrix)  have  non-prehensile  tails.  The  spider 
monkeys,  with  their  long  limbs  and  long  prehensile  tail,  are 
the  most  admirably  adapted  creatures  for  a  purely  arboreal 
life.  A  second  family  (Hapalidae)  includes  the  smallest  of  all 
monkeys,  the  marmosets.  Mostly  very  active  little  squirrel- 
like  creatures,  with  arboreal  habits,  they  are  almost  confined 
to  Brazil  and  north-western  South  America.  In  many  respects 
these  two  families  of  South  American  monkeys  are  closely 
related  to  one  another,  whereas  they  differ  from  the  Old  World 
species,  especially  in  their  dentition.  Since  no  members  of 
the  Cebidae  and  Hapalidae  have  ever  been  found  fossil  outside 
South  or  Central  America,  it  is  believed  that  they  form  a 
branch  distinct  from  the  Old  World  monkeys,  having  had  a 
separate  origin  from  lemur-like  creatures.  Dr.  Ameghino  has 
described  quite  a  number  of  lemuroid  remains  from  the  Cre- 
taceous of  Patagonia,  and  he  maintains  that  these  early  fore- 
runners of  monkeys  and  man  originated  in  the  ancient  vast 
territories  of  southern  South  America.  I  am  fully  aware  that 

*  Bates,  H.  W.,  "Naturalist  on  the  Amazons,"  p.  32. 


THE   MONKEYS   OF    SOUTH   AMERICA         365 

the  views  of  Dr.  Ameghino  *  as  to  the  age  of  these  beds  have 
received  a  considerable  amount  of  adverse  criticism.  Still, 
if  we  assume  the  correctness  of  his  arguments  and  the  former 
existence  of  a  land  bridge  between  South  America  and  Africa, 
these  lemuroid  mammals  might  have  passed  from  Patagonia, 
as  Dr.  Ameghino  supposes,  to  Africa  and  thence  to  Europe, 
and  lastly,  from  there  to  North  America.  I  do  not  think  that 
this  was  the  history  of  events.  One  distinct  branch  may 
have  travelled  from  Patagonia  to  Chile,  and  thence  direct  to 
North  America  by  a  western  land  connection  (compare 
Fig.  14),  which  I  have  already  mentioned  and  which  will  be 
further  discussed  in  the  next  chapter.  From  North  America  it 
may  have  passed  into  Europe  by  the  mid- Atlantic  land  bridge. 
I  doubt  whether  a  separate  branch  reached  Africa  from  South 
America  by  a  land  bridge,  which  Dr.  Ameghino  contends 
joined  these  two  continents.  However,  it  is  this  very  problem 
of  the  zoological  affinity  between  South  America  and  Africa 
and  its  origin  which  will  be  dealt  with  in  this  chapter. 

What  we  have  to  consider  principally,  therefore,  is 
whether  there  are  really  such  affinities  between  the  living 
faunas  of  the  two  continents  as  to  make  it  probable  that 
the  latter  were  once  connected  with  one  another  by  land. 
The  capuchin  and  marmoset  families,  which  are  quite  con- 
fined to  South  and  Central  America,  have  probably  originated 
there  in  the  remote  past  and  have  not  been  able  to  pass  into 
any  other  continent.  All  we  know  of  their  immediate  ancestry 
is  that  in  the  Eocene  deposits  of  Patagonia  a  new  family 
of  monkey-like  creatures  arose,  possessing  certain  marks  of 
resemblance  to  the  two  recent  South  American  families.  They 
were  named  "  Homunculidae  "  by  Dr.  Ameghino.  As  these 
also  are  quite  unknown  outside  South  America,  it  would 
appear  as  if  Patagonia  had  become  isolated  during  the  course 
of  the  Eocene  Period  from  the  rest  of  the  world.  We  cer- 
tainly have  no  evidence  of  any  Tertiary  land  connection 
between  the  southern  portions  of  South  America  and  Africa 
from  the  distribution  of  monkeys. 

Another  typically  Brazilian  arboreal  mammal  is  the  sloth, 
which  lazily  and  cautiously  moves  from  branch  to  branch 

*  Ameghino,  Fl.,  "  Formations  sedimentaires  de  Patagonie,"  p.  289. 


366  ORIGIN   OF   LIFE   IN   AMERICA 

supported  by  the  long  claws  of  its  toes.  Two  genera  of  this 
edentate  mammal  are  known,  viz.,  Bradypus  and  Choloepus, 
both  of  them  confined  to  South  and  Central  America,  and,  like 
the  monkeys,  absent  from  Argentina,  Chile  and  Patagonia. 
In  spite  of  their  absence  from  the  latter  country,  it  is  there, 
according  to  Dr.  Ameghino,  that  we  find  the  earliest  traces 
of  the  sloth-tribe  in  the  Eocene  beds.  The  Eocene  Entelops 
and  Trematherium  have  been  placed  into  the  same  family 
with  the  modern  sloths.  Certain  sloth-like  remains  have  even 
been  traced  back  to  the  Upper  Cretaceous  of  Patagonia. 
Sloths  of  the  arboreal  type  have  not  been  found  fossil  out- 
side South  America.  The  remains  of  a  supposed  sloth  (Brady  - 
therium)  were  discovered  by  Mr.  Grandidier  ten  years  ago 
on  the  island  of  Madagascar.  According  to  Dr.  Smith  Wood- 
ward they  belong  to  a  lemur,  yet  there  are  so  many  other 
points  of  affinity  between  South  America  and  Madagascar 
that  a  former  direct  land  connection  between  the  two  regions 
has  been  suggested.  I  return  to  this  subject  more  fully  in 
the  next  chapter. 

In  a  previous  chapter  (p.  70)  I  explained  that,  although 
all  American  porcupines  are  arboreal  in  distinction  to  the 
Old  World  species  which  live  on  the  ground,  only  the 
South  and  Central  American  forms  have  prehensile  tails. 
This  gives  them  greater  facilities  for  dispersal  in  Brazil,  and 
greater  protection  from  their  enemies.  These  South 
American  porcupines  agree  in  their  general  range  with  the 
monkeys  and  the  sloths,  and  like  them  are  absent  from  the 
southern  states  of  South  America,  although  their  ancestral 
home  was  seemingly  in  Patagonia.  Some  species  of  Coendu 
are  known  from  the  Brazilian  caves,  still,  the  centre  of  origin 
lay  manifestly  further  south. 

Of  the  pouched  or  marsupial  mammals  we  have  noticed  that 
the  opossum  has  a  wide  range  in  North  America.  In  Central 
and  South  America  the  same  North  American  species 
(Didelphys  marsupialis)  occurs  widely  distributed.  Such  an 
enormously  extensive  range  must  be  due  to  the  fact  of  its 
being  a  persistent  mammalian  type.  The  genus,  or  one 
closely  related  to  it,  certainly  was  already  represented  in  the 
Lower  Eocene  of  North  America  and  the  Upper  Eocene  of 
France.  Only  one  genus  of  these  marsupial  mammals  occurs 


SOUTH   AMERICAN   SLOTHS  367 

in  North  America.  From  South  America  three  others  are 
known.  The  general  range  of  the  family  Didelphyidae  points 
to  South  America  as  the  centre  of  dispersal.  Although  the 
genus  Didelphys  or  Peratherium  has  been  met  with  in  the 
Eocene  of  North  America  and  France,  while  it  first  appears 
in  South  America  in  the  Miocene  Period,  if  Dr.  Ameghino  is 
correct,  the  earliest  member  of  the  family  (Proteodidelphys) 
occurs  in  the  Lower  Cretaceous  beds  of  Patagonia.  Even  if 
we  look  upon  these  beds,  with  Professor  Osborn,  as  really  of 
Eocene  age,  the  more  primitive  characters  of  Proteodidelphys 
point  to  South  America  as  the  ancestral  home  of  the  family, 
and  on  this  continent  no  doubt  the  genus  Didelphys  has 
originated  a,nd  not  in  south-eastern  Asia,  as  suggested 
by  Mr.  Lydekker.*  I  think  the  geological  history  of  the 
opossums,  though  dating  further  back  than  that  of  the  South 
American  monkeys,  followed  much  upon  the  lines  of  the 
groups  just  considered,  at  any  rate,  they  seem  to  have  entered 
Brazil  about  the  same  time. 

Among  the  birds  of  South  America  we  have  precisely 
similar  examples,  except  that  in  their  case  we  know  unfor- 
tunately very  little  of  their  past  history  from  palaeontological 
evidence.  The  wonderful  family  of  humming  birds  (Trochi- 
lidae)  is  comparable  in  distribution  with  the  opossums,  in  so 
far  as  it  ranges  all  over  South  and  Central  America.  It 
has  in  all  likelihood  entered  North  America  in  later  geological 
times.  Not  a  single  species  of  humming  bird  is  known  be- 
yond the  confines  of  America.  It  is  of  importance  to  note  that 
of  the  one  hundred  and  eighteen  genera  admitted  by  Dr.  Har- 
tert,f  the  great  majority  are  confined  to  the  west  coast.  Some 
of  them  inhabit  Chile,  others  Peru,  Bolivia,  Ecuador, 
Colombia,  Central  America  and  Mexico.  A  few  (Oreotro- 
chilus)  live  at  enormous  heights,  up  to  20,000  feet.  Others 
are  limited  in  their  range  to  the  Antilles  and  Brazil.  Only 
the  single  genus  Avocettula,  with  one  species,  is  peculiar  to 
Guiana.  This  seems  to  suggest  that  the  family  originated  in 
western  South  America,  and  has  only  gradually  spread  east- 
ward on  the  mainland.  The  West  Indian  area  no  doubt  was 

*  Lydekker,  E.,  "  Geographical  History  of  Mammals,"  p.  112. 
t  Hartert,  E,,  "  Trochilidae," 


368  ORIGIN   OF   LIFE    IN   AMERICA 

invaded  by  the  humming  birds  in  earlier  times  from  the  west, 
since  several  very  distinct  genera  with  well  marked  characters 
have  originated  there.  The  humming  birds  constitute  a 
sharply  denned  family,  whose  nearest  relatives  are  the  tree- 
swifts  (Macropteryx)  of  southern  Asia  and  western  Polynesia. 
The  common  ancestors  of  these  two  groups  may  possibly 
have  inhabited  part  of  the  supposed  ancient  Pacific  continent, 
and  may  have  diverged  from  it  east  and  westward  when  it  sub- 
sided. As  Dr.  Wallace*  aptly  remarks,  no  naturalist  can 
study  in  detail  this  single  family  of  birds  without  being  pro- 
foundly impressed  by  the  vast  antiquity  of  the  South 
American  continent,  its  long  isolation  from  the  rest  of  the 
land  surface  of  the  globe,  and  the  persistence  through  count- 
less ages  of  all  the  conditions  requisite  for  the  development 
and  increase  of  varied  forms  of  animal  life. 

The  chatterers  (Cotingidae)  which  have  already  been  alluded 
to  as  comprising  some  of  the  most  beautiful  and  noteworthy 
of  American  birds,  are  almost  confined  to  South  and  Central 
America  and  the  West  Indies.  Only  a  few  species  enter  North 
America  in  Mexico.  The  curious  toucans  (Rhamphastidae) 
with  their  huge  bills  and  strange  texture  and  coloration  of 
their  plumage,  as  well  as  several  other  families,  are  restricted 
to  South  and  Central  America  and  have  no  near  relations  in 
the  Old  World. 

If  South  America  had  been  connected  by  land  with  Africa 
in  later  Tertiary  times,  we  should  expect,  at  any  rate,  such 
mobile  creatures  as  birds  and  also  butterflies  to  indicate  by 
their  distribution  the  former  existence  of  such  a  land  bridge. 
Among  the  most  conspicuous  butterflies  in  the  Brazilian 
forests,  Mr.  Bates  mentions  the  Heliconiidae,  which  are 
readily  recognisable  by  their  long  narrow  black  wings, 
variously  ornamented  with  white,  crimson  and  yellow  dots 
or  stripes.  Yet  the  family  is  almost  purely  South  American. 
A  single  species  only  (Heliconius  charitonia)  passes  into 
Mexico.f 

The  Morphidae  likewise  range  from  Argentina  to  Mexico, 
some  of  the  larger  species,  with  their  dazzling  metallic 

*  Wallace,  A.  E.,  "  Distribution  of  Animals,"  II.,  p.  9, 
t  Stichel,  H.,  and  H.  Biffarth,  "Heliconiidae," 


BIRDS  OP   SOUTH  AMERICA  369 

colours,  being  characteristic  of  the  Brazilian  forest  fauna. 
The  family  is  unknown  in  the  Old  World,  but,  as  in  the  case 
of  the  humming  birds,  we  have  closely  allied  groups  (Ama- 
thusidae,  etc.)  in  western  Polynesia  and  southern  Asia,  so 
that  the  Morphidae  or  their  ancestors  may  possibly  have 
entered  South  America,  as  so  many  other  groups  have  done, 
from  the  west. 

The  large  and  mostly  active  lizards  belonging  to  the  family 
Teiidae  are  spread  all  over  South  America,  ranging  northward 
as  far  as  California  and  Texas  and  through  the  West  Indies. 
They  appear  to  have  only  extended  their  range  into  North 
America  in  comparatively  late  geological  times,  although  they 
are  known  from  early  Tertiary  deposits  in  South  America. 
Nevertheless  the  Teiidae  are  quite  unknown  in  the  Old  World. 
Instances  of  that  kind  might  easily  be  cited  from  every  group 
of  vertebrates  and  invertebrates. 

Yet  although  these  examples  seem  to  show  that  the  faunistic 
community  between  South  America  and  Africa  is  so  slight 
as  not  to  necessitate  the  hypothesis  of  a  former  land  connec- 
tion between  these  continents,  we  possess  other  very  striking 
features  of  distribution  which  are  strongly  opposed  to  such 
a  conclusion.  I  may  draw  attention  again  to  the  most  re- 
markable fact,  pointed  out  by  Professor  Bouvier,*  that  the 
genus  Peripatus  is  peculiar  to  America,  with  the  single  ex- 
ception of  Peripatus  tholloni  of  West  Africa.  All  the  other 
Peripatus -like  creatures  have  been  proved  by  Professor 
Bouvier  to  belong  to  different  genera  or  groups. 

During  his  travels  in  the  Amazon  region,  Mr.  Bates  dis- 
covered a  curious  archaic  spider-like  creature,  which  was 
named  Cryptostemma  westermanni.  More  recently  the  same 
species  has  been  recorded  from  Sierra  Leone  and  from  the 
Cameroons  in  West  Africa.  Those  who  allege  that  accidental 
dispersal  is  responsible  for  such  cases  of  distribution,  pro- 
bably accept  the  discovery  of  Cryptostemma  westermanni 
on  both  sides  of  the  Atlantic  as  a  notable  instance  of  the 
facility  with  which  species  are  wafted  across  the  ocean.  But 
we  must  remember  that  there  are  thousands  of  species  of 
animals  and  plants  inhabiting  the  coasts  of  West  Africa  and 

*  Bouvier,  E.  L.,  "  Monographie  des  Onychophores,"  I.,  p.  91. 
L.A.  B  B 


370  ORIGIN  OP  LIFE!  IN  AMERICA 

Brazil  that  are  specifically  and  generically  distinct  from  one 
another,  although  more  fitted  for  accidental  dispersal  across 
the  ocean  than  Cryptostemma  is.  The  instances  of  such 
specific  or  generic  identity  of  animals  and  plants,  in  fact,  are 
scarce.  Moreover,  Cryptostemma  is  the  single  survivor  that 
has  yet  been  brought  to  light  of  the  otherwise  extinct  order 
Meridogastra,  which  occupies  a  somewhat  intermediate  posi- 
tion between  the  true  spiders  and  what  are  called  "harvest- 
men."*  For  this  reason  it  must,  like  Peripatus,  be  looked 
upon  as  an  exceedingly  ancient  relict  member  of  our  fauna. 

Let  us  take  another  group  of  apparently  very  ancient 
animals,  the  worm-like  and  limbless  coecilians,  which,  live 
underground.  Dr.  Boulengerf  tells  us  that  of  the  genus 
Dermophis  three  species  are  found  in  Central  and  South 
America,  one  in  West  Africa  and  another  in  East  Africa,  and 
that  the  genus  Herpele  is  confined  to  Gaboon  in  West  Africa 
and  Panama.  Dr.  Sarasin  argues  that  the  dispersal  of 
Herpele  at  any  rate  dates  from  pre-Cretaceous  times.  It 
seems  possible,  therefore,  that  these  few  archaic  creatures 
indicating  faunistic  relationship  between  South  America  and 
Africa,  have  obtained  their  present  range  during  some  very 
remote  geological  period,  when  the  conditions  of  land  and 
water  were  entirely  different  from  what  they  are  at  present, 
and  that  they  are  not  to  be  regarded  as  instances  of  accidental 
dispersal  across  the  Atlantic.  The  suggestion  that  South 
America  and  Africa  were  once  united  by  land  is  not  a  new  one. 
It  has  been  made,  as  we  have  learnt,  by  various  authorities  on 
entirely  different  grounds.  Considering  the  contradictory 
nature  of  the  evidence,  however,  the  problem  requires  close 
scrutiny. 

I  have  already  stated  that  Dr.  Ameghino  had  expressed  the 
opinion,  based  on  the  evidence  of  the  fossil  mammals,  that 
South  America  and  Africa  were  joined  by  a  land  bridge  during 
the  whole  of  Upper  Cretaceous  times.  During  the  Eocene 
Period  this  land  connection,  he  thinks,  became  more  restricted 
or  narrowed  down,  while  it  still  persisted  incompletely  as  a 
chain  of  islands,  until  middle  Miocene  times.  Dr.  Ame- 

*  Karsoh,  F.,  "  tJber  Cryptostemma,"  pp.  25—29. 

t  Boulenger,  G.  A.,  "Synopsis  of  apodal  Batrachians,"  pp.  404—409. 


FOSSIL   MAMMALS  371 

ghino's  *  arguments  in  favour  of  this  union  of  South  America 
and  Africa  are  not  founded  on  any  palaeontological  resem- 
blance between  these  two  continents,  but  rather  on  the  affinity 
of  the  fossil  mammals  of  South  America  to  those  of  Europe, 
Asia  and  North  America.  Since  I  have  shown  that  until 
about  Oligocene  times  southern  Europe  was  connected  by 
land  with  western  South  America,  by  way  of  the  West  Indies 
and  part  of  Central  America,  there  does  not  seem  to  be  any 
necessity  for  a  second  land  bridge  further  south  in  order  to 
account  for  the  mammalian  affinities  existing  between  South 
America  and  Europe  as  well  as  Asia  and  North  America. 
Professor  Osborn  does  not  recognise  the  existence  of  any 
former  land  bridge  during  the  age  of  mammals  between  South 
America  and  the  Old  World  except  by  way  of  North  America. 
Mr.  Lydekker  f  argues  that  the  only  marked  community 
between  the  Ethiopian  and  Neogaeic(  South  American)  faunas 
as  regards  mammals,  relates  to  the  hystricomorphous  rodents, 
but  he  thinks  this  community  is  a  very  marked  one  and  diffi- 
cult to  explain  on  any  other  hypothesis  than  that  of  a  land 
connection  between  the  two  areas.  The  Hystricomorpha  are 
a  section  of  the  rodent  mammals,  well  distinguished  by  mor- 
phological characters  from  the  other  sections  of  that  order. 
It  is  of  the  greatest  importance  to  note  that  this  hystrico- 
morphous section  is  now  confined  to  Africa  and  America, 
with  the  exception  of  a  couple  of  genera  which  range  into 
southern  ^Europe  and  Asia.  The  centre  of  distribution  is 
no  doubt  South  America.  If  they  had  passed  from  there  to 
Africa,  we  .should  expect  them  to  be  found  in  Brazil  and 
western  Africa.  Let  us  examine  the  two  closely  related 
families  of  Octodontidae  and  Ctenodactylidae,  which  are  in- 
cluded in  the  section  Hystricomorpha.  The  first  is  con- 
fined to  South  America,  the  other  to  Africa.  Of  the  former 
it  is  the  sub-family  Octodontinae  which  is  nearest  related 
to  the  Ctenodactylidae,  and  almost  entirely  confined  to 
Argentina  and  the  west  coast  of  South  America.  Only  a  few 
species  like  Ctenomys  brasiliensis  and  Ct.  minutus  really 
enter  Brazil.  The  extinct  species  are  all  but  one  confined  to 

*  Ameghino,  F.,  "  Formations  s6dimentaires,"  pp.  281 — 287. 
t  Lydekker,  B.,  "  History  of  Mammals,"  p.  127. 

BB  2 


372  ORIGIN   OF   LIFE   IN   AMERICA 

Argentina.  It  seems  manifest,  therefore,  that  the  ancestral 
members  of  this  sub -family  have  travelled  along  the  west 
coast  of  South  America  probably  from  a  southern  centre  of 
dispersal.  We  find  no  trace  of  them  in  Central  America  or  the 
Antilles,  but  it  is  in  North  Africa  where  we  meet  with 
Ctenodactylus  with  its  peculiarly  modified  inner  toes.  Here 
in  the  Mediterranean  region,  and  not  in  Africa  proper,  must 
have  been  the  Old  World  centre  of  dispersal,  for  we  find  the 
allied  extinct  genus  Pellegrinia  in  the  Pleistocene  of  Sicily, 
and  Ruscinomys  in  the  Pliocene  of  southern  France.  A 
recent  relation  of  Ctenodactylus  (Massoutiera)  has  passed 
southward  towards  the  Senegal.  The  main  branch,  however, 
has  apparently  invaded  eastern  Africa  from  the  Mediterranean 
region,  giving  rise  to  the  genera  Pectinator,  Thryonomys  and 
Petromys.  Only  a  single  species  (Thryonomys  swinderianus) 
has  gained  the  west  coast  of  Africa.  Of  the  sub-family 
Echimyinae,  which  largely  inhabits  Brazil,  Africa  possesses 
no  near  relations.  The  only  African  family  of  the  hystrico- 
morphous  rodents,  that  of  the  Cape  jumping  hares  (Pede- 
tidae),  occupies  a  more  isolated  position,  its  exact  relationship 
being  still  somewhat  obscure.  But  in  any  case,  I  fail  to 
deduce  sufficient  evidence  from  the  distribution  of  these 
hystricomorphous  rodents,  in  favour  of  a  direct  land  connec- 
tion between  South  America  and  Africa,  although  there  must 
have  been  one  between  the  Mediterranean  region  and  western 
South  America  by  way  of  the  West  Indies  and  Central 
America  (see  p.  280  and  Fig.  14) ., 

Apart  from  the  cape  jumping  hares  (Pededitae),  there  are 
in  South  Africa  certain  mammals  which  indicate  a  distant 
relationship  with  South  American  ones.  The  peculiar  pig- 
like  African  edentate  Orycteropus  occurs  in  Africa,  while 
another  edentate,  the  pangolin  (Manis),  inhabits  Africa  and 
the  Indian  region.  Dr.  Tullberg  thought  that  these  and  other 
features  implied  that  south-western  Africa  must  have  been 
joined  by  land  to  South  America  during  a  time  when  the 
former  was  completely  severed  from  the  rest  of  Africa.  But 
even  this  land  bridge  ceased  to  exist,  according  to  Professor 
Tullberg,*  at  the  beginning  of  the  Tertiary  Era,  at  latest  in 

*  Tullberg,  T.,  "  System  der  Nagetiere,"  p.  498. 


OLD   WOKLD   AFFINITIES  373 

Eocene  times.  He  thought  that  south-western  Africa  later  on 
became  united  with  eastern  Africa,  thus  enabling  some  of 
these  ancient  mammals  of  South  American  origin  to  spread 
northward  towards  Europe  and  eastward  into  Asia.  But  both 
the  Manidae  and  the  Orycteropidae  are  represented  in  the 
Eocene  deposits  of  southern  Europe,  while  the  genus  Orycte- 
ropus  lived  in  Samos  and  on  the  mainland  of  Greece  in  Miocene 
times.  Moreover,  neither  Manis  nor  Orycteropus  are  confined 
to  southern  Africa.  Both  are  distributed  north-eastward  as 
far  as  Kordofan  and  Senaar.  It  seems  more  likely,  therefore, 
that  these  edentates,  like  the  hystricomorphous  rodents  just 
alluded  to,  have  originated  in  the  Mediterranean  region  from 
South  American  ancestors  and  have  spread  southward  subse- 
quently. 

The  same  problem  has  also  been  discussed  by  Dr.  Andrews* 
as  the  result  of  his  remarkable  discoveries  of  fossil  mammals 
in  the  Fayum  of  Egypt.  All  the  Garni  vora  he  found  there 
belonged  to  that  archaic  group  known  as  the  "  Creodonta." 
He  argues  that  the  presence  of  these  creodonts  in  Africa  would 
account  for  the  existence  of  the  "  Sparassodonta  "  in  Pata- 
gonia, if  we  assumed  that  during  the  remote  period  when  these 
ancient  groups  originated,  Africa  and  South  America  had 
been  joined  to  one  another  by  land.  He  also  brings  forward 
another  testimony  in  support  of  his  suggestion,  which  I  shall 
deal  with  later  on.  As  for  the  Creodonta,  they  are  so  amply 
represented  in  the  early  Tertiaries  of  both  North  America  and 
Europe,  that  the  assumption  of  a  mid- Atlantic  land  bridge  is 
sufficient  to  explain  their  presence  in  these  continents  as  well 
as  in  Egypt,  while  Patagonia  must  have  had  some  land  con- 
nection with  North  America  in  late  Cretaceous  or  early 
Eocene  times. 

The  distribution  of  birds  does  not  give  us  many  definite 
suggestions  as  to  former  land  connections  between  South 
America  and  Africa.  The  range  of  the  parrots  (Psittacidae), 
however,  points  to  an  affinity  between  these  continents.  A 
more  striking  example  seems  to  be  that  of  the  ostrich  and 
rhea.  The  former  inhabits  exclusively  Africa  and  Arabia,  the 
other  Argentina  and  Brazil.  Hence  we  might  be  tempted  to 

*  Andrews,  C.  W.,  "  Tertiary  Vertebrates  of  the  Fayum,"  p.  xxii, 


374  ORIGIN   OF   LIFE   IN   AMERICA 

explain  their  present  range  by  a  direct  land  bridge  between 
the  two  continents.  The  American  ostrich  (Rhea)  is  only 
known  fossil  from  superficial  deposits,  but  the  ostrich  (Stru- 
thio)  occurs  in  the  Miocene  or  Lower  Pliocene  of  the  Siwaliks 
of  India  and  of  the  island  of  Samos.  Since  the  ostrich  once 
lived  in  the  Mediterranean  region,  it  is  possible  that  the 
common  ancestor  of  the  two  families  may  have  utilised  the 
'mid-Atlantic  land  bridge  to  travel  from  the  Old  World  to 
the  New  or  vice  versa. 

The  reptiles  and  amphibians,  as  Dr.  Blanford  *  has  pointed 
out,  indicate  a  much  more  pronounced  faunal  relationship 
between  South  America  and  Africa  than  the  birds  or  mammals 
do.  Professor  Pfeffer  f  endeavoured  to  explain  this  very  inge- 
niously by  the  assumption  of  a  former  sub -universal,  or 
almost  universal,  distribution  and  a  subsequent  extinction  on 
the  northern  continents.  He  admits  that  some  form  of 
land  bridge  was  necessary,  of  course,  yet  almost  all  inter- 
continental communication  must  have  passed,  according 
to  his  views,  across  a  Bering  Strait  land  bridge.  He 
quotes  a  number  of  instances  of  groups  which  are  now 
confined  to  the  southern  hemisphere,  but  have  once  also 
extended  to  the  northern  continents,  and  because  they 
have  done  so  he  contends  that  they  must  have  had  a 
sub-universal  distribution.  All  those  examples  which  are 
not  found  fossil  in  the  northern  hemisphere  are  nevertheless 
supposed  to  have  had  a  similar  range  and  to  have  gained  their 
present  southern  distribution  in  different  countries  by  wander- 
ing from  one  to  the  other  almost  by  way  of  the  North  Pole  and 
then  south  again.  Nothing  but  a  careful  general  study  of 
existing  distribution  can  convince  us  of  the  fallacy  of  such 
an  assumption. 

Let  us  take,  for  instance,  the  family  of  fresh- water  tortoises, 
the  Pelomedusidae.  It  is  confined  to  Africa,  including  Mada- 
gascar, and  South  America.  Curiously  enough,  one  of  the 
genera  of  this  family,  viz.,  Podocnemis  at  present  inhabits 
only  northern  South  America  and  Madagascar.  But,  as  Pro- 
fessor Pfeffer  tells  us,  the  genus  is  known  as  far  back  as 

*  Blanford,  W.  T.,  "  Anniversary  Address,"  pp.  70— 71. 

t  Pfeffer,  G.,  "  Zoogeographische  Beziehungen,"  pp.417 — 418, 


SOUTH   ATLANTIC   LAND   BRIDGE  875 

the  Cretaceous  of  Patagonia  and  New  Zealand,  the  Eocene 
of  Egypt,  England  and  India,  and  the  Miocene  of  Egypt  and 
Malta.  The  faunistic  relationship  between  Patagonia  and  New 
Zealand  will  be  explained  later  on,  yet  it  has  by  no  means  been 
produced  by  a  sub-universal  distribution.  The  only  fossil  oc- 
currence of  Podocnemis  we  know  of  from  Africa  is  that  from 
Egypt,  and  even  that,  with  Malta  and  England,  is  rather  sug- 
gestive of  a  radiation  from  a  Mediterranean  centre.  The 
dispersal  from  an  originally  Patagonian  birthplace  may  have 
taken  place  westward  to  New  Zealand  arid  northward  along 
the  ancient  land  connection,  which  I  described  as  extending 
by  way  of  Central  America  to  southern  Europe.  It  is  impor- 
tant to  bear*  in  mind  this  very  peculiar  case  of  faunistic  rela- 
tionship between  South  America  and  Madagascar,  exclusive 
of  the  African  continent,  because  similar  instances  are  met 
with  among  many  groups  of  animals  and  plants.  I  have 
already  alluded  to  one,  and  it  was  first  suggested  by  Dr. 
H.  0.  Forbes,  I  think,  that  this  range  was  due  to  a  former 
direct  land  connection  between  Patagonia  and  Madagascar. 
I  drew  attention  in  a  former  chapter  (p.  173)  to  the 
members  of  the  family  Amphisbaenidae  as  furnishing,  on 
account  of  their  subterranean  habits,  important  evidences 
of  former  changes  of  land  and  water.  I  may  men- 
tion again  that  they  are  limbless,  wormlike  liazrds,  and 
that  many  of  them  live  underground  in  ants'  nests.  They 
are  not  liable,  therefore,  to  accidental  dispersal.  Their 
distribution  is  most  interesting.  They  inhabit  mostly  Africa 
and  South  America.  A  few  occur  in  the  West  Indies  and 
the  Mediterranean  region.  Some  have  even  spread  into  the 
southern  States  of  North  America,  and  we  possess  a  few 
remains  from  Oligocene  deposits.  Otherwise  we  know  nothing 
of  their  past  history.  We  might  suppose  that  some  early  mem- 
ber of  this  family  had  spread  across  the  mid-Atlantic  land 
bridge  to  the  Mediterranean  region  and  thence  colonised 
Africa  with  Amphisbaenidae.  But  in  this  instance  such  a 
land  bridge  cannot  help  us,  because  the  genus  Amphisbaena 
occurs  in  Africa  and  South  America,  while  the  Mediterranean 
region  is  inhabited  by  the  genus  Blanus.  The  latter,  no  doubt, 
may  owe  its  origin  to  a  migration  across  this  mid- Atlantic 
land  bridge,  still  we  can  scarcely  imagine  that,  coming  from 


376  OKIGIN   OF   LIFE   IN   AMERICA 

the  north,  and  after  having  given  rise  to  Blanus  in  southern 
Europe,  the  American  ancestor  reverted  again  to  Amphisbaena 
when  it  reached  Africa.  Amphisbaena,  moreover,  is  represented 
in  Brazil  by  about  a  dozen  species,  some  of  which  are  very 
closely  allied  to  those  of  Sierra  Leone  and  Liberia  in  West 
Africa.  If  we  attribute  such  a  range  to  a  former  sub-universal 
distribution,  as  Professor  Pfeffer  suggests,  then  practically 
all  animals  with  a  wide  southern  range  must  at  some  time  or 
other  have  passed  through  'North  America  and  Asia  or  Europe 
to  roach  their  present  habitats,  and  for  such  an  assumption 
we  have  no  palaeontologies!  evidence.  I  think  a  case  of  this 
kind,  as  Dr.  Blanford  remarks,  implies  a  former  land  con- 
nection between  South  America  and  Africa.  We  possess 
among  the  Amphisbaenidae  an  even  more  striking  example  of 
faunal  relationship  between  these  two  continents.  There  are 
two  species  of  Anops,  one  of  which  (Anops  kingi)  ranges 
from  Brazil  to  Argentina,  while  the  only  other  species  (A. 
africanus)  is  confined  to  West  Africa. 

Of  particular  interest  are  the  skinks  (Scincidae),  as  I 
explained  (p.  124)  that  this  family  must  be  of  very  great 
antiquity.  Some  of  the  genera  certainly  date  back  to  Meso- 
zoic  times.  Now,  while  skinks  are  abundant  in  North 
America,  the  southern  continent  is  almost  entirely  free 
from  these  lizards.  Those  that  live  there,  at  any  rate, 
belong  to  a  genus  distinct  from  the  northern  one.  Southern 
Asia  and  Africa  are  the  headquarters  of  this  large  family. 
Only  the  single  genus  Mabuia  has  spread  into  South 
America.  Mabuia  occurs  principally  in  southern  Asia, 
Madagascar  and  Africa.  A  few  species  are  known  from 
the  Cape  Verde  islands  on  the  west  coast  of  Africa, 
while  one  (Mabuia  punctata),  very  closely  allied  to  them, 
has  been  met  with  on  the  island  of  Fernando  de  Noronha 
off  the  east  coast  of  South  America  and  also  in  Guiana. 
Three  species  are  found  in  Brazil.  A  couple  have  passed 
northward  penetrating  into  Central  America  and  one  even 
to  the  Greater  Antilles.  We  have  clear  evidence  here  of 
a  former  land  connection  between  West  Africa  and  South 
America  and  of  its  having  been  utilised  by  the  skink,  Mabuia, 
in  traversing  the  Atlantic  in  a  westward  direction. 

The  worm-like   amphibian  Dermophis  has   not  yet  been 


LIZARDS,   FROGS   AND   TOADS  377 

noticed  in  eastern  South  America,  but  to  judge  from  the  cir- 
cumstance that  one  species  lives  in  east  Africa,  another  in  west 
Africa,  a  third  in  Ecuador,  and  a  fourth,  in  Central  America, 
according  to  Dr.  Boulenger,*  we  may  conclude  that  the  genus 
will  probably  turn  up  in  Guiana. 

The  frogs  and  toads  are  divided  into  two  groups,  one  of  which 
(a  very  small  one)  contains  those  that  are  devoid  of  a  tongue, 
while  all  others  possess  this  useful  organ.  The  tongueless 
toads  are  generally  looked  upon  as  the  most  primitive  of  the 
tailless  amphibians.  Three  genera  of  these  creatures  are 
known  to  science,  two  (Xenopus  and  Hymenochirus)  inhabit- 
ing Africa  south  of  the  Sahara,  the  other  (Pipa)  eastern 
South  America.  The  only  member  of  the  last  genus  is  the 
remarkable  Surinam  toad  (Pipa  americana)  whose  skin  on 
the  back  of  the  female  is  provided  with  pits  in  which  the 
eggs  are  placed  and  the  young  undergo  their  whole  metamor- 
phosis. These  tongueless  toads  (Aglossa)  are  not  known 
as  fossils.  We  have  thus  to  conjecture  the  origin  of  their  dis- 
persal from  their  present  distribution  which  is  highly  sug- 
gestive of  a  former  direct  land  bridge  between  Africa  and 
South  America.  This  view  is  considerably  strengthened  by 
the  fact  that  the  West  African  Hymenochirus  is  in  several 
respects  more  closely  related  to  Pipa  than  to  Xenopus. 

The  toothless  frogs  (Dendrobatidae)  appear  at  first  sight 
to  be  typical  examples  of  a  group  which  has  obtained  its  pre- 
sent range  by  means  of  a  former  land  bridge  between  South 
America  and  Africa.  They  occur  only  in  northern  South 
America,  in  west  Africa  and  Madagascar,  a  discontinuous  dis- 
tribution which  betokens  antiquity,  and  which  is  not  unknown 
among  other  animals  and  plants.  Yet  Dr.  Gadowf  argues 
that  the  Old  World  and  New  World  genera  were  evolved  inde- 
pendently from  toothed  frogs,  that  this  is,  in  fact,  a  case  of 
convergence.  It  may  be  so,  but  his  arguments  are  by  no 
means  convincing. 

I  may  once  more  be  permitted  to  draw  attention  here  to 
the  opinion  long  ago  expressed  by  Dr.  Gill  J  that  fishes  are 

*  Boulenger,  G.  A.,  "  Synopsis  of  apodal  Batrachians,"  p.  404. 

t  Gadow,  H.,  "Amphibia  and  Eeptiles,"  p.  272. 

I  Gill,  T.,  "  Principles  of  Zoogeography,"  pp.  29—30, 


378  ORIGIN   OF   LIFE    IN   AMERICA 

among  the  best  indicators  of  past  continental  changes, 
and  that  the  relations  of  the  several  southern  continents  as 
to  their  ichthyio  faunas  can  be  best  understood  by  the  assump- 
tion that,  at  some  remote  epoch  or  epochs,  there  was  distribu- 
tion of  land  and  water  which  eventually  permitted  an  emigra- 
tion and  immigration  of  types  from  one  into  another.  Dr. 
Giinther  *  enunciated  similar  views.  He  thought  that  the 
existence  of  so  many  similar  forms  of  fishes  on  both  sides  of 
the  southern  Atlantic  supported  the  supposition  that  they  are 
the  descendants  of  a  common  stock  which  had  its  home  in  a 
region  now  submerged  under  some  intervening  part  of  the 
ocean.  Since  the  days  when  these  two  great  authorities  pro- 
nounced upon  this  subject,  the  ichthyology  of  both  Africa  and 
South  America  has  become  better  known,  and  new  light  has 
been  thrown  on  the  relationship  between  the  various  groups 
of  fishes.  We  can  deal  with  the  problem  now  in  the  light  of 
the  latest  researches.  Dr.  Boulenger  has  made  a  special  study 
of  the  African  fish  fauna,  while  Mr.  Regan  and  Professor 
Eigenmann  have  paid  particular  attention  to  the  ichthyology 
of  South  America.  In  his  interesting  address  to  the  British 
Association  on  the  distribution  of  African  fishes  Dr.  Bou- 
lenger mentions  Protopterus  as  the  most  noteworthy  fish  of 
Africa.  In  some  respects  it  approaches  the  amphibia.  It 
possesses  a  double  lung  as  well  as  gills,  and  is  able  to  live  for 
a  long  period  in  dried  mud.  Anatomically  there  are  many 
characters  in  which  it  differs  from  almost  all  other  fishes. 
Its  only  living  relation,  Lepidosiren  of  Brazil,  is  very  similar 
in  form  and  so  closely  allied  that  the  two  are  placed  into 
the  same  family  Lepidosirenidae.  Professor  Pf effer  f  con- 
tends that  since  this  family  is  represented  in  the  Permian 
and  Trias  of  western  North  America,  in  the  Trias  of  India 
and  South  Africa,  in  the  Cretaceous  of  Patagonia  and  the 
Trias  and  Jurassic  of  Europe  it  must  have  had  a  universal  dis- 
tribution. Hence  he  argues  that  the  occurrence  of  Pro- 
topterus in  Africa  and  of  Lepidosiren  in  South  America  can 
have  no  significance  in  supporting  the  theory  of  a  former 
land  connection  between  these  two  continents.  But  recent 

*  Gunther,  Albert,  "  Study  of  Fishes,"  p.  233. 

t  Pfeffer,  G.,  "  Zoogeographische  Beziehungen,"  p.  433. 


THE   FISHES   OF   SOUTH   AMERICA  379 

researches  have  shown  that  these  extinct  forms  all  belong 
to  the  genus  Ceratodus,  that  all  are  members  of  the  family 
Ceratodidae.*  The  only  fossil  member  of  the  Lepidosirenidae 
is  Protopterus  libycus  of  Egypt.  There  is  really  no  reason, 
therefore,  as  Dr.  Boulenger  f  puts  it,  why  the  latter  family 
should  not  have  passed  from  one  of  the  two  continents  into  the 
other  when  they  were  connected  by  land. 

Another  striking  feature  of  the  South  American  fresh-water 
fish  fauna  is  the  extraordinary  number  and  variety  of  forms 
of  the  Characinidae,  unquestionably,  according  to  Dr.  Bou- 
lenger,  one  of  the  most  lowly  and  generalised  groups  of  ex- 
clusively fresh-water  teleosts.  They  are  likewise  abundantly 
represented  in  western  and  central  Africa,  yet  not  a  single 
genus  is  common  to  both  continents.  Hence  Dr.  Boulenger  J 
concludes  that  it  is  quite  legitimate  to  explain  the  distribu- 
tion of  this  family  by  the  assumption  of  a  land  bridge  con- 
necting Africa  and  South  America  about  the  end  of  the 
Cretaceous  Period. 

A  similar  argument  is  used  by  Mr.  Began  §  to  account  for 
the  large  fresh-water  family  Cichlidae  (compare  Fig,  12)  in 
these  two  continents,  except  that  he  is  of  opinion  that  the 
land  bridge  was  still  in  existence  in  early  Eocene  times. 

Professor  Eigenmann  ||  states  that  there  is  no  known  means 
by  which  these  two  families  could  have  crossed  the  existing 
gap  between  Africa  and  South  America.  There  has  been  no 
exchange  of  species  in  recent  times,  for  there  is  no  species 
or  genus  common  to  the  two  continents.  The  South  American 
and  African  elements  of  these  two  families  must  have  been 
derived  from  some  intermediate  land-mass,  or  must  have 
travelled  from  one  continent  to  the  other  over  a  land  bridge. 
That  this  connection  must  have  been  obliterated  before  the 
Tertiary  Era  is  evidenced,  he  remarks,  by  the  fact  that  the 
Tertiary  deposits  of  Taubate  and  Parana  include  existing 
genera,  and  that  many  South  American  families  of  fishes 

*  Goodrich,  E.  S.,  "  Cyclostomes  and  Fishes,"  p.  258. 
t  Boulenger,  G.  A.,  "  Distribution  of  African  Fishes,"  p.  5. 
J  Boulenger,  G.  A.,  "  Distribution  of  African  Fishes,"  p.  6. 
§  Eegan,  T.,  "  Fishes  of  Central  America,"  p.  xiv. 
||   Eigenmann,  0.,  "  Fishes  of  South  and  Middle  America,"  pp.  525— 
526, 


380  ORIGIN   OF   LIFE   IN   AMERICA 

which  are  absent  from  Africa  have  arisen  in  South  America 
from  the  Characinidae  and  Siluridae  since  the  separation  of 
the  two  continents. 

Dr.  von  Ihering's  early  recognition  of  the  importance  of 
fresh-water  faunas  as  an  aid  to  the  palaeogeographical  studies 
of  the  Palaeozoic  and  Mesozoic  Eras,  has  led  to  very  remark- 
able results.  Some  of  these  I  have  indicated  already.  His 
noteworthy  discovery  that  some  of  the  fresh-water  bivalves 
of  South  America  have  a  "  lasidium "  larva,  while  all  the 
Unionidae  possess  a  "  glochidium,"  placed  the  family  Mute- 
lidae  into  quite  a  different  position.  The  Mutelidae  are  a 
family  essentially  South  American  and  African,  demonstrat- 
ing clearly,  as  Dr.  von  Ihering  *  admits,  the  existence  of  a 
land  connection  between  South  America  and  Africa  during  the 
Mesozoic  Era. 

The  family  Achatinidae  includes  some  of  the  largest  and 
most  conspicuous  land-snails,  Achatina  achatina  growing  to  a 
length  of  seven  inches.  Their  distribution,  which  is  well 
known,  indicates  an  African  centre  of  evolution.  The  early 
members  of  the  family  are  unknown  and  should  be  looked  for 
in  mid-Mesozoic  deposits,  according  to  Dr.  Pilsbry.f  The 
same  authority  believes  that  some  of  the  sections  o'f  the  Acha- 
tinidae migrated  to  South  America  before  the  interruption  of 
the  land  connection  across  the  tropical  Atlantic.  Dr.  Pilsbry, 
who  in  his  earlier  volumes  condemns  the  practice  of  throwing 
hypothetical  bridges  across  the  oceans,  now  almost  takes  it  as 
a  matter  of  course  that  Africa  and  South  America  were  once 
united  by  land.  The  mollusks,  as  most  other  groups  of 
animals,  yield  facts  of  distribution  that  are  quite  unexplain- 
able  by  the  theory  of  accidental  dispersal,  and  many  of  those 
who  at  first  were  firm  believers  in  the  immutability  of  our 
ocean  basins,  have  entirely  changed  their  opinions  after  a 
careful  study  of  zoogeography.  It  is  the  smaller  kinds  of  the 
Achatinidae  which  show  the  affinity  between  the  two  con- 
tinents most  clearly.  Thus  the  genus  Subulina  is  confined  to 
Africa  and  tropical  America  while  Opeas  and  Pseudopus  have 
spread  to  other  parts  as  well. 


*  IherinT,  H.  von,  "  Archhelenis  and  Archinotis,"  pp.  125 — 145. 
t  Pilsbry,  H.  A.,  "  Manual  of  Conchology,"  Vol.  XVIIL,  p.  vi, 


FAUNISTIC   PKOBLEMS  381 

It  is  now  fifty  years  since  Mr.  Andrew  Murray  *  first 
directed  attention  to  the  fact  that  the  beetle  fauna  of  Old 
Calabar  in  West  Africa  presented  certain  affinities  with  that 
of  South  America.  He  even  then  suggested  that  some  sort  of 
•communication  must  once  have  existed  between  these  two 
regions  of  the  earth.  A  few  years  later  he  returned  to  the 
same  problem,  expressing  the  opinion  that  this  communica- 
tion consisted  of  an  actual  land  bridge  of  which  the  only  re- 
maining vestiges  are  the  islands  of  Ascension,  St.  Paul's,  St. 
Helena  and  Tristan  da  Cunha.f 

Great  stress  is  also  laid  on  this  remarkable  relationship 
between  the  southern  continents  by  Professor  Kolbe,J  but  he 
explains  it  by  the  assumption  of  a  land  bridge  far  to  the 
south  of  the  Equator. 

Dr.  Packard  §  was  good  enough  to  inform  me  some  years 
ago  that  the  distribution  of  the  Lepidoptera  was  distinctly 
in  favour  of  the  theory  of  a  former  union  between  South 
America  and  Africa.  He  alluded  in  particular  to  a  family  of 
moths  known  as  the  Saturnidae,  stating  that  their  general 
range  confirmed  the  view  arrived  at  from  other  sources,  that 
perhaps  at  the  close  of  the  Cretaceous  Period  and  through 
the  early  part  of  the  Tertiary  Era  the  two  continents  were 
connected  with  one  another  by  land. 

The  importance  of  the  fresh-water  crabs  in  the  solution  of 
problems  of  this  nature  has  been  emphasised,  as  I  mentioned 
before,  by  Dr.  Ortmann,||  who  showed  that  the  west  African 
Potamoninae  are  geographically  most  closely  approached  by 
the  South  American  Potamocarcininae,  and  that  this  suggested 
a  former  union  of  these  regions.  This  land  bridge  in  its  full 
extent,  he  thinks,  existed  during  the  Jurassic  and  in  early 
Cretaceous  time.  In  the  middle  of  the  Cretaceous  Period  the 
southern  Atlantic  advanced  northward  and  gradually  invaded 
the  east  coast  of  South  America  extending  as  far  as  the 
Amazon  valley.  Guiana  still  remained  joined  to  West  Africa 

during  the  remainder  of  the  Cretaceous  Period,  and  was  not 

• 

*  Murray,  A.,  "  Coleoptera  of  Old  Calabar,"  pp.  453—454. 
t  Murray,  A.,  "  Coleopterous  Faunae,"  p.  15. 
|  Kolbe,  H.  J.,  "  Die  Coprophagen  Lamellicornier,"  p.  503. 
§  Packard,  A.  S.,  "  Larval  Forms  of  Moths,"  p.  280. 
||  Ortmann,  A.  E.,  "Distribution  of  Decapods,"  pp.  350—351. 


382  ORIGIN   OF   LIFE   IN   AMERICA 

finally  destroyed  until  early  Tertiary  times  (compare  Figs.  15 
and  20).  Quite  recently,  however,  Dr.  Ortmann  *  argued  that 
this  "  Archhelenis "  of  Dr.  von  Ihering  must  have  sunk 
beneath  the  waves  of  the  ocean  by  the  end  of  iJie  Mesozoic  Era. 

Some  time  ago  Mr.  Pocock  f  pointed  out  that  the  scorpions 
of  the  genus  Opisthacanthus  were  confined  to  tropical  Africa, 
Madagascar  and  South  America.  Our  knowledge  of  the  dis- 
tribution of  scorpions  has  increased  considerably  since  he 
wrote  his  essay,  but  the  range  of  Opisthacanthus  has  not  been 
greatly  extended.  It  occurs  in  west,  east  and  south  Africa 
and  Madagascar,  while  it  reappears  on  the  opposite  side  of  the 
Atlantic  in  Colombia  and  the  island  of  Haiti.  It  is  not  known 
from  either  Brazil  or  Guiana  and  may  possibly  have  become 
extinct  there.  On,  the  other  hand,  Damon,  one  of  the  Tarantu- 
lidae,  occurs  in  west  and  east  Africa  and  from  Brazil  to  Pata- 
gonia. Professor  Kraepelin  |  assumes  that  because  the  African 
Damon  variegatus  in  a  specifically  identical  form  actually 
inhabits  South  America,  it  must  have  been  introduced  into  the 
latter  continent,  yet  in  another  place  he  urges  that  several 
of  the  centipedes  (Scolopendridae)  probably  maintained  their 
Bpecific  characters  from  archaic  times  to  the  present  day.  Like 
some  of  the  species  of  Otooryptops,  Rhysida  and  Scolopendra 
and  the  curious  arachnid  Cryptostemma,  Damon  variegatus 
may  possibly  represent  one  of  these  ancient  species  which 
has  retained  its  morphological  characters  unchanged  since 
Mesozoic  times. 

The  numerous  examples,  cited  above,  indicate  that  there 
exists  a  perfectly  recognisable  faunistic  relationship  between 
tropical  Africa  and  tropical  South  America.  Nevertheless  this 
relationship  rarely  extends  to  genera  and  species.  If  so  it  is 
confined  to  forms  like  Anops,  'Mabuia,  Subulina,  Opistha- 
canthus, Cryptostemma  and  others,  of  which  there  is  reason 
to  believe  that  they  are  extremely  ancient  types.  From  some 
cause  or  other  they  may  have  retained  their  specific  or  generic 
characters  throughout  a  series  of  geological  ages.  The  faunas 
of  Africa  and  South  America  as  a  whole  are  thoroughly  dis- 

*  Ortmann,  A.  E.,  "  Tertiary  Archhelenis,"  p.  242. 
t  Pocock,  E.  I.,  "  Distribution  of  Arachnida,"  p.  229. 
|  Kraepelin,  K,  "  Scorpiones  and  Pedipalpi,"  p.  240. 


VON  IHERING'S  BESEAECHES  383 

tinct.  All  the  more  modern  families  of  these  continents  show 
scarcely  any  traces  of  relationship  to  one  another.  Conse- 
quently we  must  conclude  with  Dr.  Ortmann  and  several  other 
authors  who  have  definitely  expressed  themselves  on  the  geo- 
logical age  of  the  former  land  bridge  between  South  America 
and  Africa,  that  the  latter  ceased  to  exist  before  Tertiary 
times. 

Dr.  von  Ihering*  did  not  limit  his  studies  in  South  America 
to  the  fauna,  he  likewise  urged,  contrary  to  the  opinion 
held  by  most  botanists,  that  the  floras  of  South  America  and 
Africa  pointed  unmistakably  to  the  existence  of  his  "  Arch- 
helenis."  His  arguments  were  so  convincing  that  Professor 
Englerf  adopted  his  views  after  a  very  careful  and  critical 
examination  of  the  problem  from  a  botanical  aspect.  He  ac- 
knowledged that  for  a  long  time  he  had  looked  upon  the  theory 
of  a  former  land  connection  between  South  America  and  Africa 
with  scepticism,  chiefly  on  account  of  the  great  intervening 
ocean  depths  and  the  marked  endemism  in  the  flora  of  the  two 
continents.  After  discussing  the  various  means  of  accidental 
dispersal,  and  eliminating  those  plants  which  might  possibly 
owe  their  presence  in  both  continents  to  some  of  the  known 
modes  of  occasional  transport,  he  was  impressed  by  the  cir- 
cumstance that  there  was  still  a  residuum  of  species,  genera 
and  families  which  must  have  had  another  origin.  He  urged 
that  the  distribution  of  the  Strelitzioidae,  whose  fruits  cannot 
be  dispersed  by  wind,  also  that  of  some  of  the  water  plants  of 
Africa,  which  have  very  near  relations  in  South  America,  and 
others  might  be  accounted  for  by  the  supposition  of  the  former 
existence  of  a  series  of  large  islands  in  the  Atlantic  Ocean 
separated  by  narrow  channels.  All  the  same  he  prefers  a 
complete  land  bridge  between  the  two  continents. 

Dr.  Aj-ldt  J  discusses  the  problem  in  a  very  effectual  manner 
both  from  a  biological  and  a  geological  point  of  view.  Like 
Dr.  Ameghino,  however,  he  is  led  to  the  conclusion  that  even 
in  early  Tertiary  times  South  America  was  still  directly  joined 


*  Ihering,  H.  von,  "  Das  Neotropische  Florengebiet." 
f  Engler,  A.,    "  Floristische    Verwandtschaft    zwischen    Afrika    and 
Amerika,"  pp.50 — 51. 

|  Arldt,  Th.,  "  Entwicklung  der  Kontinente,"  p.  451, 


384  OBIGIN   OF   LIFE   IN   AMERICA 

to  Africa,  whereas  I  favour  the  theory  that  such  a  connec- 
tion could  only  have  persisted  indirectly  by  way  of  the  Antilles 
and  southern  Europe. 

It  has  been  urged  that  if  a  land  bridge  had  once  existed 
between  Brazil  and  west  Africa  we  ought  to  find  some  traces 
of  sedimentary  rocks  on  the  few  islands  that  are  scattered 
about  in  the  intermediate  area,  like  Fernando  de  Noronha,  St. 
Paul's,  St.  Helena,  Ascension  and  Tristan  da  Cunha,  whereas 
all  these  are  believed  to  be  composed  of  volcanic  rocks.  Pro- 
fessor Schwarz,*  nevertheless,  affirms  that  although  Ascen- 
sion consists  of  volcanic  rock  the  substratum  is  granitic.  St. 
Paul's  island,  he  thinks,  is  mainly  metamorphic  in  structure, 
and  there  are  signs  of  its  having  been  subjected  to  considerable 
earth  movements.  Continental  types  of  rocks  occur  on  Tristan 
da  Cunha.  Consequently  Professor  Schwarz  concludes  that 
these  Atlantic  islands  furnish  some  geological  testimony  for 
the  belief  in  a  Mesozoic  Continent  in  the  position  of  the 
southern  Atlantic  lasting  until  the  beginning  of  the  Tertiary 
Era. 

The  island  of  Fernando  de  Noronha  lies  about  two  hundred 
miles  east  of  Cape  San  Koque  on  the  coast  of  Brazil.  Since 
its  discovery  in  1503  both  the  original  fauna  and  flora  of  the 
island  have  been  laid  waste  by  early  settlers,  so  that  only 
vestiges  of  these  are  left.  The  splendid  trees  that  once  clothed 
the  island  are  gone  and  with  them  probably  the  greater  part 
of  the  fauna.  A  mammal,  at  any  rate,  existed  on  Fernando  de 
Noronha  when  it  was  discovered,  but  it  has  quite  vanished. 
Mr.  Eidley,  who  visited  Fernando  de  Noronha  in  1887,  noticed 
that  quite  a  number  of  species  of  animals  and  plants  had  evi- 
dently been  introduced  by  human  agency.  Many  others,  he 
thinks,  have  been  transported  to  the  island  from  the  main- 
land by  winds,  although  he  noted  that  the  smaller  birds  and 
a  large  proportion  of  the  smaller  insects  are  endemic.  A  few, 
he  remarks,  may  possibly  have  been  brought  over  on  the  feet 
of  wading  birds.  There  still  remains  a  small  group  of  indi- 
genous species  which  are  difficult  to  account  for,  on  the  hypo- 
thesis of  accidental  distribution.  The  subterranean  lizard 

*  Schwarz,  E.  H.  L.,   "Land-connection  between  Africa  and     ^uth 
America,"  pp.  81—90. 


FEBNANDO   DE    NOEONHA  385 

Amphisbaena  ridleyi,  for  example,  is  peculiar  to  the  island, 
its  nearest  relation  living  in  the  West  Indies.  The  skink 
(Mabuia  punctata)  occurs  on  the  island  as  well  as  in  British 
Guiana.  The  snail  Bulimulus  ridleyi,  as  I  have  already 
pointed  out  (p.  176),  is  the  only  living  representative  of  the 
Oligocene  group  of  species  which  once  inhabited  Florida. 
There  are,  moreover,  two  species  of  Opeas  identical  with  West 
Indian  forms,  while  a  Pupa  seems  closely  allied  to  a  Cuban 
species.  The  single  fresh-water  species  (Planorbis  noron- 
hensis)  is  endemic.  The  noteworthy  relationship  with  the 
Antilles  is  also  noticeable  among  the  plants  as  well  as  among 
the  marine  forms  living  on  the  snores  of  the  island.  As  might 
be  expected,  this  is  attributed  by  Mr.  Ridley  *  to  the  action 
of  sea-currents.  No  other  theory  of  the  origin  of  the  fauna 
and  flora  of  Fernando  de  Noronha  than  that  of  accidental 
dispersal  by  wind  or  waves  ever  occurred  to  him.  Yet  both 
Mabuia  and  Amphisbaena  are  genera  which,  as  I  have  shown, 
can  be  cited  with  some  justification  as  evidences  of  the  exist- 
ence of  a  former  land  connection  between  South  America  and 
West  Africa.  And  these,  with  a  gecko  of  enormously  wide 
range,  constitute  the  only  members  of  the  reptilian  fauna. 
Why  should  these  ancient  reptiles  inhabit  Fernando  de 
Noronha  and  not  any  of  the  more  modern  groups  ?  This 
and  other  pertinent  criticisms  of  Mr.  Eidley's  theory  have 
also  been  urged  by  Dr.  von  Ihering,f  who  shows,  especially 
from  a  botanical  point  of  view,  that  accidental  dispersal  has 
not  played  a  very  important  part  in  the  origin  of  the  island 
flora.  On  the  contrary,  he  maintains  that  it  is  part  of  the 
ancient  Archhelenis  which  once  united  South  America  and 
Africa. 

The  small  island  of  Trinidad,  not  to  be  confounded  with  the 
island  of  the  same  name  in  the  West  Indies,  lies  much  further 
south,  and  about  seven  hundred  miles  east  of  the  coast  of 
Brazil.  It  is  now  uninhabited,  though  for  a  time  it  contained 
a  small  colony  of  settlers  who  left  a  few  goats  and  pigs  on  the 
island,  which  continued  the  destruction  of  the  native  fauna 
and  flora  commenced  by  their  late  masters.  The  ground 

*  Eidley,  H.  N.,  "  Zoology  of  Fernando  Noronha,"  pp.  473 — 502. 
t  Ihering,  H.  von,  "Fernando  de  Noronha,"  p.  6. 

L.A.  C  C 


386  OKIGIN   OF   LIFE   IN   AMERICA 

moreover,  is  riddled  with  the  burrows  of  myriads  of  land 
crabs,  which  have  aided  the  domestic  animals,  to  the  best  of 
their  ability,  in  this  work.  Trinidad  seems  to.  have  been 
densely  wooded  formerly  with  tree  ferns,  palms,  etc.,  whereas 
living  trees  are  now  confined  to  the  mountain  tops.  Among 
the  ferns  collected  on  the  island  by  Dr.  Copeland  *  there  was 
one  (Asplenium  compressum)  hitherto  only  observed  in  St. 
Helena.  Of  the  fauna  nothing  appears  to  be  known. 

Ascension  island  lies  in  about  the  middle  of  the  southern 
Atlantic.  When  Darwin  visited  the  island  during  his  famous 
voyage  round  the  world,  he  found  little  there  of  interest.  A 
principal  mound  in  the  centre  looks  as  if  i't  were  the jyarent  of 
the  lesser  volcanic  cones  studded  round  the  island.  The  sur- 
face is  parched  and  barren,  and  everything  presents  a  scene 
of  utter  desolation.  Yet  not  only  is  Ascension  island  in- 
habited, the  scanty  pasture  has  even  been  made  serviceable 
for  a  number  of  sheep,  goats  and  cows.  Ascension  stands  on  a 
submarine  bank  about  two  hundred  miles  in  length.  It  is 
probable  on  that  account  that  the  existing  island  only  repre- 
sents the  last  remnant  of  a  cluster  of  volcanic  cones  which 
rose  high  above  the  surrounding  land.  The  surviving  fauna 
and  flora  are  extremely  poor.  Many  of  the  species,  like  the 
centipede  Scolopendra  morsitans,  are  almost  cosmopolitan  in 
their  range,  a  few  also  occur  in  Africa  or  South  America. 
But  no  effort  has  as  yet  been  made  to  conduct  a  thorough 
zoological  and  botanical  survey  of  the  island,  and  it  is  to  be 
hoped  that  this  will  be  accomplished  before  all  traces  of  the 
ancient  relicts  that  might  still  occur  have  been  superseded 
by  recent  importations.  At  any  rate,  nothing  of  any  impor- 
tance can  be  gathered  from  the  little  information  we  possess. f 

St.  Helena,  like  Ascension  island,  is  wholly  volcanic  in 
structure,  and  being,  moreover,  surrounded  by  depths  up  to 
17,000  feet,  Dr.  Wallace  claims  that  we  ought  to  be  satisfied 
as  to  its  being  a  true  oceanic  island  and  as  to  its  owing  none  of 
its  peculiarities  to  a  former  union  with  any  continent  or  other 
distant  land.  But,  as  I  have  pointed  out  once  before,  the  exis- 
tence of  such  a  great  depth  of  the  ocean  does  not  prove  that  it 

*  Copeland,  R.,  "  Insel  Trinidad,"  pp.  274—277. 

t  Gimther,  A.,  and  others,  "  Collection  made  in  Ascension  Island." 


ST.   HELENA  AND   ITS   FAUNA  387 

always  was  so.    Geological  evidence,  says  Professor  Suess,* 
does  not  prove,  nor  even  point  to,  a  permanence  of  the  great 
depths,  at  least  in  the  oceans  of  the  Atlantic  type.    No  longer 
can  we,  therefore,  subscribe  to  Dr.  Wallace's  statement  that 
St.    Helena    is    necessarily   what   he    calls    a  "true  oceanic 
island."     The  island  was  densely  covered  with  a  luxuriant 
forest  vegetation  when  it  was  discovered  in  the  year  1501. 
Human    occupation   has    almost   wholly   destroyed   this    in- 
digenous vegetation,  and  with  it  no  doubt  the  greater  part  of 
the  fauna.    The  rich  soil,  no  longer  protected  by  the  covering 
vegetation,  has  been  swept  away  by  tropical  rains,  leaving  a 
vast  expanse  of  bare  rock  or  sterile  clay.     Fortunately  the 
fauna  and  flora  of  St.  Helena  have  received  greater  attention, 
than  those  of  Ascension,  and  although  a  mere  fragment  only  of 
what  originally  inhabited  this  area,  it  allows  us  to  draw  some 
conclusions  as  to  their  origin.     There  are  neither  mammals, 
amphibians  nor  reptiles  on  the  island.     The  only  indigenous 
bird  is  a  small  plover  (Aegialitis  sanctae-helenae),  closely  allied 
to  a  species  found  in  South  Africa.   Among  the  invertebrates 
the  beetles  in  particular  have  been  carefully  studied  by  Mr. 
T.  V.  Wollaston.f     Out  of  two  hundred  and  three  species 
collected  on  the  island,  he  considers  one  hundred  and  twenty- 
nine  to  he  indigenous.      Only  one  of  these  is  found  else- 
where.      These   species   belong   to    thirty-riine   genera,    of 
which  no  less  than  twenty-five  are  peculiar  to  St.   Helena, 
most  of  them  being   weevils    (Ehynchophora).       Since  the 
greater  number   of   weevils    are   woodborers,    we    conclude 
from  this  fact  alone  that  the  island  once  possessed  a  luxuriant 
forest  vegetation.    Many  of  the  beetles  show  no  close  affinity 
with  any  existing  insects.     A  small  number  only  are  more 
or   less   remotely   related   to   European   and    South  African 
species.    These  features  imply,  as  Dr.  Wallace  truly  remarks, 
that  the  beetle  fauna  of  the  island  is  extremely  ancient,  dating 
back  to  at  least  the  Miocene  age.   Dr.  Wallace  acknowledges 
that  at  present  the  marine  currents  flow  towards  St.  Helena 
from  the  region  of  the  Cape  of  Good  Hope ;  nevertheless  he 
contends  that  in  former  geological  periods  the  currents  may 

*  Suess,  E.,  "  Are  Ocean  Depths  Permanent  ?  "  p.  186. 
t  Wollaston,  T.  V.,  «'  Coleoptera  Sanctae  Helenae." 

c  c  2 


388  ORIGIN   OF   LIFE   IN   AMERICA 

have  varied,  and  that  drift-wood  might  have  been  carried  to 
the  island  from  different  directions.  Great  alterations  of 
wind,  he  thinks,  were  probable  during  the  Glacial  Epoch,  so 
that  these  two  most  potent  agencies  in  the  accidental  trans- 
port of  species  may  have  varied  very  much  during  the  periods 
in  which  the  island  received  its  colonists  from  other  countries. 
Of  course,  Dr.  Wallace*  firmly  adheres  to  the  belief  that  all 
animals  and  plants  found  on  the  island  owe  their  existence 
there  to  some  means  of  occasional  transport. 

Thirty  species  of  bugs  (Hemiptera)  have  been  recorded  by 
Dr.  White  from  St.  Helena,  of  which  five  have  certainly,  and 
one  probably,  'been  introduced.  This  leaves  twenty-six  species 
indigenous  to  the  island.  Of  the  twenty-one  genera  of  Hemip- 
tera eight  are  peculiar  to  St.  Helena,  but  the  general 
distribution  of  these  insects  was  so  little  known  at  the  time 
that  Dr.  White  was  unable  to  trace  their  affinities,  except  that 
most  of  them  have  a  wide  range,  and  several  are  known  from 
Miocene  deposits.  Only  one  genus  (Megarhaphis)  has  dis- 
tinctly African  affinities.  Dr.  White  f  argues  from  the 
general  aspect  of  the  fauna  and  flora,  from  the  non-existence 
of  mammals  and  reptiles,  from  the  large  number  of  endemic 
species,  and  from  the  great  depth  of  the  surrounding  sea,  that 
St.  Helena  at  no  time  could  have  been  joined  by  land  with 
Africa  or  South  America.  A  careful  consideration  of  all  the 
known  facts  led  him  to  believe  that  the  colonists  did  not  arrive 
all  in  a  body,  but  that  colonisation  was  spread  over  a  con- 
siderable period.  He  rejects  the  theory  of  a  continuous  land 
surface,  contending  that  the  fauna  and  flora  arrived  from  the 
north  in  the  direction  of  the  Cape  Verd  islands.  Stepping- 
stones  in  the  shape  of  islands,  now  disappeared,  may  have 
existed  formerly,  thus  facilitating  dispersal,  whilst  the 
marine  currents  were  probably  reversed. 

Mr.  Pickard-CambridgeJ  informs  us  that  forty-four  species 
of  spiders  are  known  from  the  island,  some  of  them  being  also 
found  in  Europe,  and  two  in.  Egypt.  The  rest  are  endemic, 
but  most  of  them  show  European  relationship.  In  a  former 

*  Wallace,  A.  E.,  "  Island  Life,"  pp.  294—303. 

t  White,  F.  B.,  "Hemiptera  of  St.  Helena,"  pp.  446—460. 

t  Pickard-Cambridge,  O.,  "  Spiders  of  St.  Helena,"  p.  210. 


THE   INSECTS   OF   ST.   HELENA  889 

ncte  he  recorded  two  scorpions  (Lychas  maculatus  and  L. 
americanus).  These  have  since  been  shown  to  be  both  forms 
of  Isometrus  maculatus,  a  cosmopolitan  species  of  the  tropical 
and  sub-tropical  zone.  In  Europe  it  occurs  only  in  the  south 
of  Spain.* 

The  total  number  of  land-shells  indigenous  to  St.  Helena 
is  estimated  by  Mr.  Smith  as  amounting  to  twenty-seven 
species.  With  regard  to  their  origin,  he  likewise  rejects  the 
theory  of  a  possible  land  connection  of  the  island  with  either 
Africa  or  South  America,  or,  indeed,  any  other  land  surface. 
All  the  same,  he  points  out  that  there  is  a  greater  resemblance 
between  the  molluscan  fauna  of  St.  Helena  and  South 
America  than  was  recognised  by  previous  observers.  It  is 
especially  a  species  resembling  the  exclusively  Brazilian 
genus  Tomigerus  that  seemed  to  Mr.  Smith  to  point  to  South 
America  as  the  likely  source  of  some  of  the  indigenous  species. 
He  does  not  feel  tempted  to  probe  further  into  this  mystery, 
for  he  exclaims,  "  How  they  were  transmitted  is  a  hopeless 
problem  to  solve,  and  although  drift-wood,  carried  by  oceanic 
currents,  is  doubtless  answerable  for  a  good  deal  in  the  way 
of  distribution  the  subject  must  apparently  ever  remain  one 
of  mere  speculation."  Nevertheless  Dr.  Kobelt  f  regards  it  as 
highly  probable  that  this  molluscan  fauna  is  the  last  remnant 
of  that  of  an  ancient  Mesozoic  continent. 

About  half  of  the  species  of  the  snails  of  St.  Helena  are 
now  extinct  and  occur  only  in  a  sub-fossil  condition.  Hyalinia 
cellaria,  H,  alliaria  and  a  few  others,  along  with  Amalia 
(Milax)  gagates  are  supposed  to  have  been  introduced  with 
plants.  It  is  quite  possible  that  some  of  them  were  brought 
to  St.  Helena  in  that  manner,  still  it  is  very  remarkable  that 
the  only  slug  thus  conveyed  should  be  one  of  our  raxest 
British  species,  and  the  one  which  has  the  widest  range  of  all 
slugs.  It  occurs  in  California,  New  Zealand,  and  other  remote 
localities,  while  none  of  our  common  Arions,  Agriolmiaces 
or  Limaces  have  found  their  way  to  the  island.  I  am  fully 
convinced  that  Amalia  gagates  is  one  of  the  most  ancient  of 
our  European  terrestrial  species,  as  I  explained  in  a  previous 

*  Pickard-Cambridge,  O.,  "  Spiders  and  Scorpions  of  St.  Helena,"  p.  544, 
f  Kobelt,  W.,  "  Zoogeographische  Stellung  von  St.  Helena,"  p.  201. 


390  ORIGIN   OF  LIFE   IN   AMERICA 

chapter  (p.  213),  and  that  it  might  well  form  part  of  the 
indigenous  fauna  of  the  island.  There  are  twelve  species, 
some  of  which  greatly  resemble  Polynesian  forms,  as  Mr. 
Smith  pointed  out,  and,  indeed,  Dr.  Pilsbry  has  placed  them 
provisionally  with  Endodonta,  a  genus  otherwise  confined  to 
Australia  and  Polynesia.  There  are  three  species  of  Succinea, 
a  genus  which  seems  to  be  particularly  unfit  for  transport 
on  drift-wood,  while  the  most  striking  members  of  the  snail- 
fauna  are  a  species  of  Bulimus,  seven  species  of  Bulimulus, 
and  one  provisionally  placed  by  Mr.  Smith*  in  the  South 
American  genus  Tomigerus. 

More  recently,  Dr.  Pilsbry  demonstrated  that  these 
apparently  bulimoid  snails  are  really  members  of  the  family 
Achatinidae,  and  that  they  all  belong  to  the  genus  Chilonopsis. 
Since  all  the  nearest  relations  of  Chilonopsis  are  African 
genera,  the  affinity  of  this  group  is  with  Africa  rather  than 
with  South  America.  But  the  great  antiquity  of  Chilonopsis 
is  indicated  by  the  fact  that  Trichodina,  to  which  it  is  closely 
allied,  has  a  most  remarkably  discontinuous  range,  occurring 
only  on  some  islands  off  the  coast  of  West  Africa  and  on  the 
Comoro  islands  in  East  Africa.  Chilonopsis,  moreover,  is 
more  primitive  than  the  genera  of  the  large  African  Achati- 
nidae, and  Dr.  Pilsbryf  expresses  the  opinion  that  it,  as  well 
as  the  related  genera,  originated  from  a  common  ancestor 
which  lived  in  Mesoaoic  times,  when  Africa  and  South 
America  were  united  by  land.  None  of  the  species  have  any 
affinity  with  South  African  ones,  as  was  supposed  to  be  the 
case  among  the  Hemiptera. 

Although  Dr.  White's  Megarhaphis  has  now  been  shown 
to  belong  to  Macrorhaphis,  a  genus  confined  to  Africa, 
two  species  have  since  been  taken  in  west  Africa. 
The  supposed  slight  affinity  of  the  St.  Helena  bugs  to 
those  of  the  Cape  has  therefore  entirely  disappeared.  As 
regards  the  pronounced  European  element  in  the  St.  Helena 
insect  fauna,  it  is  probably  to  a  large  extent  of  American 
origin.  The  beetle  Zophobas  morio  lives,  outside  St.  Helena, 
only  in  west  Africa,  Central  and  South  America  and 

*  Smith,  E.  A.,  "  Land-shells  of  St.  Helena,"  pp.  259—269. 
t  Pilsbry,  H.,  "  Manual  of  Conchology  (Pulmonata)  "  (2),  Vol.  XVII., 
pp.  171—173. 


ANTIQUITY   OF   INSECT  FAUNA  391 

the  Antilles,  while  all  other  members  of  the  genus  are 
American.  The  only  relation  of  the  bug  Metacanthus  con- 
color  of  St.  Helena  occurs  in  Europe,  whereas  the  three  most 
closely  tallied  genera  inhabit  America.  The  genus  Nysius 
has  a  world-wide  range,  and  is  known  from  American  Miocene 
deposits.  Cardiastethus  occurs  in  Europe  as  well  as  in  St. 
Helena,  but  the  genus  is  mostly  American,  and  from  there 
ranges  across  the  Pacific  to  New  Zealand.  Nabis  capsiformis 
occurs  in  southern  Europe,  and  also  all  over  Africa  and 
America,  while  the  genus  has  a  world-wide  range.  The  allied 
Vernonia  of  St.  Helena  has  near  relatives  in  the  West  Indies 
and  the  western  Pacific  region.  Salda  is  a  distinctly  northern 
genus,  although  a  few  species  reappear  far  southward  of 
the  others  in  Chile,  New  Zealand  and  St.  Helena.  That  such 
a  range  implies  great  generic  antiquity  is  evident,  and, 
indeed,  Salda  is  known  in  several  species  from  the  lower 
Oligocene. 

Of  the  Curculionidae  which  are  so  largely  represented  in  the 
fauna  of  St.  Helena,  and  which  Dr.  Wallace  thought  might  be 
of  Miocene  age,  many  recent  genera  are  now  known  from  the 
Lower  Oligocene  and  they  are  probably  much  older  even  than: 
that,  for,  according  to  Dr.  Handlirsch,  over  two  hundred 
species  are  now  known  from  Oligocene  deposits.  The  genus 
Homalota  which  Dr.  Wallace  fancied  was  exclusively  Euro- 
pean, is  represented  in  the  Oligocene  of  North  Am'erica. 
Philonthus,  Xantholinus  and  Oxytelus  occur  in  the  American 
Miocene  and  European  Lower  Oligocene.  The  supposed 
European  genera  of  insects  inhabiting  St.  Helena  are  thus 
mostly  groups  of  very  wide  range,  or  such  of  which 
we  actually  possess  palaeontological  evidence  of  their  having 
existed  since  early  Tertiary  times. 

However  ancient  the  insect  fauna  may  be,  remarks  Dr. 
Wallace,  the  flora  must  be  more  ancient  still.  Of  the  fifty 
truly  indigenous  flowering  plants,  about  forty  are  peculiar 
to  St.  Helena,  and  of  twenty-six  ferns,  about  ten.  The  re- 
lationship of  this  flora  is  mainly  African,  according  to  Sir 
Joseph  Hooker,  whereas  Mr.  Bentham  maintains  that  the 
Compositae  have  their  affinities  for  the  most  part  with  South 
America.  Sixteen  species  of  ferns  are  common  to  St.  Helena 


392  ORIGIN   OF  LIFE   IN   AMERICA 

and  other  countries.  Dr.  Wallace,*  however,  acknowledges 
that  specific  identity  among  ferns  does  not  necessarily  imply 
a  recent  origin.  According  to  Professor  Engler  f  the  five 
endemic  genera  are  somewhat  related  to  American  ones, 
whereas  some  species  of  Pelargonium,  Mesembryanthemum, 
Wahlenbergia  and  Oteospermum  must  have  originated  in 
Africa. 

Dr.  von  Ihering  J  discusses  all  the  various  modes  of  dis- 
persal, by  birds,  winds  and  ocean  currents,  in  connection 
with  the  origin  of  the  flora  of  St.  Helena,  and  rejects  them 
as  quite  inefficient.  In  his  opinion,  only  a  land  connection 
with  Africa  and  South  America  could  have  produced  the  flora. 

Although  St.  Helena  is  surrounded  by  great  ocean  depths, 
and  possesses  neither  mammals,  reptiles  nor  amphibians,  we 
cannot  assume,  as  Dr.  Wallace  has  done,  that  the  whole  fauna 
and  flora  owe  their  origin  to  accidental  dispersal  by  birds, 
winds  and  ocean  currents.  If  such  were  the  case,  there  is  no 
reason  why  these  modes  of  transport  should  not  have  been 
equally  effective  in  Pliocene  and  Pleistocene  times  than  in  the 
older  geological  periods,  and  why  there  should  not  be  many 
species  differing  but  slightly  from  American  or  African  ones. 
Everything,  on  the  other  hand,  points  to  the  animals  and 
plants  being  almost  all  of  extreme  antiquity.  We  have  either  to 
suppose,  therefore,  that  during  some  very  remote  period  the 
modes  of  transport  alluded  to  were  far  more  efficient  than  they 
are  now,  or  that  St.  Helena  was  connected  by  land  with  South 
America  and  Africa.  For  many  reasons,  already  fully  dis- 
cussed in  this  chapter,  the  latter  hypothesis  appears  to  me 
the  only  one  that  is  at  all  probable.  If  we  assume  that  there 
was  such  a  land  bridge,  it  is  quite  possible  that  the  actual 
volcanic  area  now  forming  St.  Helena  was  not  in  existence, 
but  originated  after  portions  of  the  land  connection  had 
already  subsided.  A  mere  remnant  of  the  fauna  and  flora 
would  eventually  have  taken  refuge  on  the  rock  of  St.  Helena, 
whilst  the  surrounding  country  disappeared  beneath  the 
floods.  Whether  in  early  Tertiary,  or  even  in  later  Tertiary 
times,  there  was  a  short  and  independent  land  bridge  between 

*  Wallace,  A.  K.,  "  Island  Life,"  pp.  305—307. 

t  Engler,  A.,  "  Entwicklungsgeschichte  der  Florengebiete,"  II.,  p.  179. 

I  Ihering,  H.  von,  "  Das  neotropische  Florengebiet,"  p.  50. 


TRISTAN  DA   CUNHA  393 

St.  Helena,  Ascension  island,  the  Cape  Verd  islands,  the 
Canaries  and  Madeira,  is  a  matter  which  must  be  left  to  future 
observations.  Certain  faunistic  features  appear  to  be  in 
favour  of  such  a  theory. 

Tristan  da  Cunha  is  almost  as  large  as  St.  Helena.  It 
lies  considerably  further  south,  being  bleak  and  inhospitable 
in  the  extreme,  owing  to  its  proximity  to  the  northern  boun- 
dary of  the  antarctic  ice-drift.  The  flora  is  quite  different 
from  that  of  St.  Helena,  as  it  possesses  antarctic  affinities. 
The  genera  Nertera,  Uncinia  and  Acaena  inhabiting  antarctic 
America,  New  Zealand  or  Australia  occur  here  also.  It  has 
Lomaria  alpina,  in  common  with  South  America,  Kerguelen 
island,  New  Zealand  and  Australia,  while  Spartina  arundi- 
nacia  occurs  in  Tristan  da  Cunha  and  St.  Paul,  and  is  related 
to  a  South  American  species.*  The  most  remarkable  member 
of  the  fauna  is  the  genus  Tristania  which,  with  its  two  species, 
is  confined  to  the  island.  It  is  related  to  th© snail  Opeas  which 
inhabits  both  Africa  and  South  America. 

Almost  three  hundred  miles  further  south  there  is  still  an- 
other volcanic  island,  of  which  scarcely  anything  was  known 
until  it  was  visited  by  Dr.  Bruce,  the  leader  of  the  Scottish 
National  Antarctic  Expedition.  First  called  "  Diego 
Alvarez  "  according  to  Dr.  Brown,f  its  name  was  later  on 
changed  to  "  Gough  island."  The  island  differs  from  some 
of  the  other  islands  referred  to,  in  being  densely  covered  with 
vegetation,  which  is  similar  in  character  to  that  of  Tristan 
da  Cunha.  While  showing  the  same  general  affinities,  Diego 
Alvarez  seems  to  have  a  stronger  American  element  than  the 
islands  forming  the  Tristan  da  Cunha  group.  The  land  birds 
comprising  two  species  of  bunting  (Nesospiza)  and  a  galli- 
nule  (Porphyriornis)  are  peculiar  to  the  island,  but  related 
to  species  living  on  Tristan  da  Cunha. 

To  briefly  review  the  results  of  our  studies  so  far,  it  appears 
highly  probable  that  Brazil  was  entirely  separated  from 
western  South  America  in  Mesozoic  and  part  of  Tertiary 
times,  but  was  connected  with  the  highland  of  Guiana  across 
the  mouth  of  what  is  now  the  Amazon  river,  which  flowed 

*  Engler,  A.,  "  Entwicklungsgeschichte  der  Florengebiete,"  II.,  p.  159. 
t  Brown,  E.  N.  E.,  "  Diego  Alvarez,"  pp.  9—10. 


394  OKIGIN   OF  LIFE   IN   AMEKICA 

westward.  During  part  of  Secondary  times  eastern  Brazil 
was  most  likely  united  by  land  with  West  Africa.  During  the 
Cretaceous  age  already,  the  southern  Atlantic  rapidly  advanced 
northward,  invading  eastern  Brazil,  so  that  the  land  bridge 
then  joined  only  northern  South  America  and  a  small  tract 
of  West  Africa.  In  Eocene  times  the  southern  trans -Atlantic 
land  connection  had  ceased  to  exist,  yet  the  South  American 
continent  must  have  extended  still  far  eastward  of  its  present 
coast-line.  Eastern  Brazil  continued  to  receive  new  additions 
to  its  fauna  from1  the  northern  States  of  South  America  while 
its  area  extended  gradually  westward.  When  Brazil  finally 
became  joined  to  Argentina  a  faunistic  interchange  took 
place,  although  Brazil  and  Chile  remain  to  the  present  day 
two  fundamentally  distinct  countries. 


CHAPTER  XV 

ARGENTINA    AND    CHILE 

ALTHOUGH  the  natural  southern  boundaries  of  Brazil  appear 
to  be  the  great  river  Plate  and  the  Paraguay  river  (Fig.  18), 
the  two  smaller  republics  of  Uruguay  and  Paraguay  are  inter- 
posed between  Brazil  and  this  river  system,  while  Argentina 
has  also  claimed  a  large  slice  of  territory  on  the  northern  side 
of  it.  As  we  proceed  southward  from  eastern  Brazil  the  moun- 
tains gradually  pass  into  hills  which  again  are  replaced  by 
gently  undulating  plains.  Magnificent  pasture  lands  abound 
in  Uruguay,  accompanied  by  a  mild  and  healthy  climate,  so 
that  the  country  is  well  adapted  for  the  staple  industry, 
which  consists  in  raising  horses  and  cattle.  The  spurs  of 
the  eastern  highlands  of  Brazil  are  still  recognisable  in  the 
northern  provinces  of  Argentina,  where  they  are  covered  by 
extensive  forests  of  algaroba,  cedar  and  other  trees,  thus 
greatly  adding  to  the  natural  resources  of  that  wealthy 
country.  The  surface  of  the  remainder  of  the  great  Argen- 
tine Republic  is  largely  occupied  by  somewhat  monotonous 
tracts  of  low  and  nearly  level  land,  here  and  there  relieved  by 
small  groups  of  mountain  ranges  which  seem  mostly  to  have 
some  connection  with  the  foothills  of  the  Andean  mountain 
chain.  The  whole  of  western  Argentina  again  is  very  moun- 
tainous and  well  wooded.  The  highest  summit  of  the  Andes, 
Aconcagua  (23,080  feet),  actually  lies  in  Argentine  territory. 
Beyond  the  crest  of  this  immense  mountain  chain,  occupying 
an  elongated  narrow  strip  of  country  along  the  shores  of  the 
Pacific  Ocean,  lies  the  Republic  of  Chile.  The  upheaval  of 
the  Cordillera  of  the  Andes,  separating  the  two  states,  must 
have  been  the  result  of  movements  of  the  earth's  crust  which 
occurred  long  after  the  formation  of  the  rocks  composing  the 
range. 

With  these  alterations  in  the  topography  and  climate  as 


396  ORIGIN   OF   LIFE   IN   AMERICA 

we  proceed  southward,  the  fauna  and  flora  gradually  undergo 
a  complete  change.  On  leaving  the  forest,  monkeys,  sloths 
and  other  animals,  bound  to  an  arboreal  life,  are  replaced  by 
new  types,  unknown  in  Brazil,  such  as  the  Patagonian  hare 
and  vizcacha.  A  very  characteristic  faunistic  feature  of  the 
Argentine  "  pampas,"  as  the  humid  grassy  country  is  called, 
is  the  presence  there  of  the  American  representative  of  the 
ostrich.  This  rhea  is  quite  absent  from  the  vast  forests  of 
Brazil.  In  the  northern  parts  of  that  country,  however,  where 
we  again  meet  with  grass  lands,  this  flightless  bird  reappears 
as  a  memento  of  the  times  when  north  and  south  were  joined 
by  continuous  prairies.  We  thus  have  some  noteworthy 
instances  of  discontinuous  distribution  suggesting  a  former 
period  when  the  drying  up  of  vast  lakes,  perhaps,  may  have 
given  rise  to  grass  lands,  which  enabled  certain  southern  types 
to  push  northward.  Other  Argentine  animals,  such  as  the 
coypu  (Myocastor  coypus),  one  of  the  largest  of  the  rodent 
tribe,  have  apparently  invaded  Brazil  in  more  recent  times, 
for  they  have  only  entered  the  southern  and  western  pro- 
vinces. To  those  unacquainted  with  the  past  history  of  South 
America  it  must  come  as  a  matter  of  surprise  that  the  only 
ungulate  which  is  noticed  in  these  vast  pampas  of  Argen- 
tina is  a  deer,  closely  related  to  the  true  North  American  deer 
(Odocoileus  virginianus)  and  its  allies.  I  have  expressed  my 
belief  above  (p.  Ill)  that  the  true  American  deer  owe  their 
origin  to  one  or  more  ancestors  which  passed  into  South 
America  directly  from  Europe,  and  it  is  important  to  note 
that  the  centre  of  dispersal  of  the  various  groups  in  South 
America  lies  in  the  western  states.  Only  a  couple  of  species 
are  peculiar  to  Brazil.  All  the  others  are  more  or  less 
confined  to  the  western  states.  Even  the  distribution  of  the 
South  American  wolves  led  Dr.  von  Ihering  *  to  the  similar 
conclusion  that  these  animals  entered  the  continent  from  the 
west. 

Mr.  W.  H.  Hudson  f  gives  us  a  vivid  idea  of  the  life  in  the 
pampas  of  Argentina,  the  striking  poverty  of  its  fauna  as 
compared  with  Brazil,  and  all  the  more  characteristic  features 

*  Ihering,  H.  von,  "  Siidamerikamsche  Raubtiere,"  p.  162. 
t-Hudson,  W.  H.,  "  Naturalist  in  La  Plata." 


THE   FAUNA  OF  AKGENTINA  397 

of  that  remarkably  fertile  country,  which  has  lately  become 
a  centre  of  attraction,  not  only  from  a  point  of  view  of 
agriculture,  but  as  a  treasure-house  of  palaeontological 
records. 

Argentina  must  have  undergone  very  notable  physio- 
graphical  and  climatic  changes  within  the  Tertiary  Era.  As 
Dr.  White  *  has  pointed  out,  the  whole  of  the  coast-line  from 
Eio  de  Janeiro  southward  appears  to  present  evidences  of 
submergence.  Eivers,  bays  and  islands  exhibit  an  aspect 
of  drowning  similar  to  that  shown  by  the  rivers  and  bays  of 
Nova  Scotia,  Cape  Breton  and  Newfoundland;  and  the  amount 
of  coastal  depression  seems  to  increase  southward,  judging 
by  borings  for  harbour  works  at  Bio  de  Janeiro  and  at 
Pelotas. 

The  presence  of  terrestrial  and  fresh -water  deposits  to  a 
depth  of  nearly  a  thousand  feet  below  the  city  of  Bu,enos 
Aires  implies,  as  Dr.  Ameghino  f  remarks,  that  here  also  the 
continent  extended  formerly  much  further  eastward.  The 
same  author  contends,  in  fact,  that  the  whole  of  the  southern 
Atlantic  is  of  Tertiary  age.  I  am  not  prepared  to  concur  in 
this  view,  but  it  can  scarcely  be  doubted  that  Argentina  had 
in  later  Tertiary  times  at  any  rate  a  much  greater  area  than 
at  present. 

It  is  now  more  than  twenty  years  since  Dr.  Ameghino  first 
made  known  to  the  world  that  an  extraordinary  wealth  of 
animal  life  once  tenanted  the  vast  plains  of  Argentina.  Not 
only  in  early  Tertiary  deposits;  even  in  late  Mesozoic  beds 
were  found  the  bones  of  mammals  belonging  to  many  different 
groups.  The  origin  of  life,  at  least  of  the  higher  animals,  was 
always  looked  for  in  the  north.  Dr.  Ameghino's  discoveries, 
which  certainly  rank  among  the  most  noteworthy  that  have 
ever  been  made  in  palaeontology,  riveted  attention  for  the 
first  time  to  the  southern  hemisphere.  No  wonder  that  Dr. 
Ameghino  J  in  his  enthusiasm  pronounced  Argentina  to  be 
the  original  home  of  all  the  mammals  of  the  world. 


*  White,  I.  C.,  "Relatorio  final  de  estudos  das  minas,"  p.  3. 
f  Ameghino,  PL,  "  Formations  sedimentaires,  p.  29. 
|  Ameghino,  PL,    "South  America   as  the  Source    of    Mammalia," 
p.  260. 


398  OKIGIN   OF   LIFE   IN   AMEEICA 

Naturally  his  views  gave  rise  to  a  considerable  amount  of 
discussion  jand  criticism  among  geologists  and  palaeontolo- 
gists ;  and  many  visited  the  scenes  of  these  startling  dis- 
coveries. Almost  all  of  them  felt  convinced  that  Dr. 
Ameghino  had  wrongly  interpreted  the  age  of  the  deposits 
alluded  to.  They  thought  that  the  fossiliferous  beds  described 
must  be  much  more  recent  than  Dr.  Ameghino  supposed,  and 
that  at  any  rate  South  America  was  certainly  not  the  source  of 
all  the  mammalia.  One  of  the  richest  of  the  deposits  exposed 
in  different  parts  of  Patagonia,  especially  in  the  region  of  the 
Santa  Cruz  river,  and  hence  spoken  of  as  the  "  Santa  Cruz 
beds,"  is  considered  by  Dr.  Ameghino  as  of  Upper  Eocene 
and  Lower  Oligocene  age.  Almost  all  other  authorities  believe 
them  to  belong  to  the  Miocene.  The  latter  view  seems  to  be 
strengthened  by  the  results  of  the  study  of  the  marine  shells 
contained  in  beds  of  similar  age  which  were  pronounced  by 
Dr.  Ortmann  *  to  be  of  Miocene  Age.  As  Professor  Scott  f 
expresses  the  opinion  that  Dr.  Ortmann  has  clearly  demon- 
strated the  Miocene  age  of  the  Santa  Cruz  beds,  I  should  like 
to  direct  attention  to  a  more  recent  work  dealing  with  this 
problem.  Its  author,  Dr.  von  Ihering,J  has  made  a  special 
study  for  many  years  past  of  the  marine  mollusks  of  South 
America.  Hence  his  opinion  is  of  particular  value.  After 
a  long  and  careful  study  of  a  larger  series  of  fossil  mollusks 
than  was  available  before,  he  came  to  the  conclusion  that 
the  marine  Cretaceous  deposits  of  Patagonia  pass  very  gradu- 
ally into  those  of  the  next  formation,  which  is  the  one 
described  by  Dr.  Ortmann,  the  latter  scarcely  containing 
five  per  cent,  of  living  species.  He  is  inclined  on  that 
account  to  agree  with  Professor  Ameghino  as  to  the  Eocene 
and  Oligocene  age  of  these  marine  beds,  and  thus  indirectly 
with  his  general  scheme  of  correlation.  Dr.  von  Ihering's 
arguments  appear  to  me  more  convincing  than  those  of  Dr. 
Ameghino's  opponents,  and  I  shall  therefore  adhere  to  the 
latter's  nomenclature  of  the  Argentina  deposits.  Not  only 
has  Dr.  von  Ihering  adopted  Dr.  Ameghino's  views,  they 

*  Ortmann,  A.  E.,    "Princeton   University    Expedition,"    Vol.  IV., 
p.  317. 

t  Scott,  W.  B.,  "Mammalian  fauna  of  Santa  Cruz,"  p.  241. 
|  Ihering,  H.  von,  "Mollusques  fossiles  de  PArgentine,"  p.  95. 


AMEGHINO'S   DISCOVEKIES  399 

have  partially  been  accepted  also  by  Dr.   Koth,*  who  has 
personally  studied  the  problems  on  the  spot. 

As  regards  the  mammalian  remains  contained  in  the  Santa 
Cruz  terrestrial  beds,  Professor  Scott  f  was  greatly  struck 
by  the  strangeness  of  the  assemblage.  Not  a  single  genus 
occurs  in  any  part  of  the  northern  hemisphere.  Some  of  the 
orders  even  of  mammals  are  distinct  from  those  of  the 
northern  faunas.  Thus  the  beds  have  yielded  no  carnivores, 
no  modern  groups  of  ungulates  nor  elephants,  while  the 
rodents  all  belong  to  the  section  Hystricomorpha.  The  place 
of  the  carnivores  was  taken  by  carnivorous  marsupials,  some- 
what resembling  the  Tasmanian  wolf  (Thylacinus).  Numbers 
of  small  plant-eating  marsupials,  of  which  Caenolestes 
(see  p.  350)  is  an  interesting  survival,  likewise  occur.  One  of 
the  largest,  most  varied  and  most  characteristic  elements  of 
the  Santa  Cruz  fauna  are  the  edentates.  They  are  repre- 
sented by  the  Dasypoda  or  armadillos,  the  greater  part  of 
whose  skin  is  strongly  ossified,  the  scutes  forming  a  great 
shield  over  the  body,  and  by  the  Glyptodontia  and  the  Gravi- 
grada.  The  last  two  groups  are  now  extinct.  The  glyptodonts 
resembled  armadillos,  except  in  so  far  as  the  bony  scutes  were 
joined  into  a  solid  mass  like  the  shield  of  tortoises,  while  the 
Gravigrada  or  ground  sloths  were  extraordinarily  varied  and 
numerous.  Only  a  single  genus  (Necrolestes)  of  Insectivora 
has  been  obtained  in  the  Santa  Cruz  beds,  as  already  alluded 
to  (p.  246).  At  present  this  order  is  quite  unknown  in 
South  America.  The  ungulates  belong  to  the  extinct  groups 
Toxodontia,  Astrapotheria  and  Litopterna.  The  toxodonts 
were  represented  by  the  genus  Nesodon  which  somewhat  re- 
sembled a  rhinoceros  in  shape  and  had  similar  teeth.  Of  the 
second  group  very  little  is  as  yet  known,  while  the  Litopterna 
are  the  most  remarkable  of  all  the  hoofed  animals.  Without 
being  in  any  way«  related  to  the  horse-tribe,  certain  genera 
have  paralleled  the  structure  of  the  horse-foot  in  a  most 
wonderful  way,  giving  the  latter  a  striking  and  deceptive  re- 
semblance to  that  of  the  ancient  Hipparion.  The  animals 
afford,  indeed,  as  Professor  Scott  remarks,  one  of  the  most 

*  Roth,  S.,  "  Sedimentablagerungen  in  Patagonien." 

t  Scott,  W.  B.,  "  Mammalian  fauna  of  Santa  Cruz,"  pp.  242—247. 


400  ORIGIN   OF  LIFE   IN   AMEEICA 

remarkable  and  instructive  examples  of  convergent  develop- 
ment among  mammals.  Finally  the  Santa  Cruz  beds  contain 
the  remains  of  monkeys  of  South  American  type.  The  earliest 
traces  of  mammalian  remains  in  Patagonia  were  supposed  to 
have  been  found  together  with  the  bones  of  dinosaurs.  Since 
these  reptiles  are  characteristic  of  the  Mesozoic  Era,  the  state- 
ment that  they  were  contemporaneous  with  rather  advanced 
types  was  at  first  treated  with  little  credence,  especially  as 
the  actual  deposits  were  not  examined  by  Dr.  Ameghino  * 
but  by  his  brother.  Dr.  Both,  however,  has  since  re-examined 
the  localities  in  question  and  has  met  with  mammalian  re- 
mains partly  mixed  with  those  of  dinosaurs,  and  partly  resting 
actually  below  the  latter,  so  that  there  is  scarcely  any  doubt 
as  to  the  correctness  of  the  original  observation.  The 
mammals  belong  to  peculiar  mastodon-like  ungulates,  having 
been  placed  in  the  order  Pyrotheria  which  is  now  extinct  and 
quite  confined  to  Patagonia.  Others,  such  as  Notostylops,  be- 
long to  the  Toxodontia  above  alluded  to. 

I  think  there  is  a  general  agreement  now  that,  at  any  rate 
at  the  dawn  of  the  Tertiary  Era,  a  number  of  rather 
specialized  groups  of  mammals  lived  in  Patagonia,  and, 
although  some  of  them  became  extinct,  others  continued 
to  inhabit  the  country  until  recent  geological  times.  A  few 
of  the  largest  edentates,  like  the  giant  ground  sloth  Mega- 
therium, which  was  about  the  size  of  an  elephant,  and  is 
supposed  to  have  dragged  down  trees  in  order  to  feed  on  the 
leaves,  rather  than  climb  up  like  its  modern  diminutive  rela- 
tion the  tree-sloth,  still  roamed  about  the  country  in 
Pleistocene  times. f  A  few  years  ago  the  dried  skin,  with  hair 
still  attached  to  it,  of  a  huge  creature  was  discovered  in  a  cave 
in  southern  Patagonia,  near  the  boundary  between  Argentina 
and  Chile.  It  proved  to  belong  to  the  ground  sloth  Neomy- 
lodon,  now  known  as  Grypotherium  listai.J  Later  on,  the 
bones  of  the  animal  were  disinterred,  along  with  those  of  an 
extinct  horse  and  a  large  carnivore.  Traces  of  a  fire  were 
also  noticed  and  an  enclosure  with  cut  hay.  From  these  evi- 

*  Ameghino,  Fl.,  "Formations  sedimentaires,"  p.  80. 

t  Lankester,  Bay,  "  Extinct  Animals,"  p.  172. 

t  Moreno,  F.  P.,  and  A.  Smith  Woodward,  "Neomylodon  listai." 


FOSSIL   EDENTATES  401 

dences  of  man's  presence,  along  with  the  remains  of  the 
ground  sloth,  it  was  concluded  that  the  cavern  was  an  old 
corral  in  which  the  ground  sloths  had  been  kept  and  tended 
by  some  primitive  human  race.* 

The  survival  of  many  of  such  large  creatures  until  recent 
geological  times  implies  that,  as  in  the  northern  hemisphere, 
there  must  have  been  ample  food  available  in  Argentina 
during  the  Pliocene  and  Pleistocene  Periods  to  nourish  these 
mammals,  the  climatic  conditions  having  since  become  more 
varied  and  unfavourable.  Compared  with  the  Santa  Cruz 
edentates,  the  less  ancient  groups  were  mostly  larger. 

In  spite  of  the  fact  that  the  fossil  mammalian  fauna  of 
Argentina  presents  so  many  features  pointing  to  long  isola- 
tion, the  relationship  of  certain  forms  to  those  found  in  far 
distant  regions  is  of  extreme  interest  and  importance  from  a 
zoogeographical  point  of  view,  as  elucidating  the  geological 
history  of  the  South  American  continent.  The  diversity  in 
shape  and  character  between  the  Santa  Cruz  armadillos 
(Dasypoda),  for  example,  is  very  notable,  according  to  Pro- 
fessor Scott,f  no  less  than  three  families  and  seven  genera 
having  been  described  so  far.  And  yet  a  genus  of  armadillo 
(Metacheiromys)  makes  its  appearance  in  the  Middle  Eocene 
beds  of  western  North  America.  Dr.  Wortman's  theory  that 
the  edentates  were  of  North  American  origin,  having  sub- 
sequently spread  to  South  America,  has  not  been  adopted  by 
any  later  authors.  Dr.  Wortman  assumed  that  their  earliest 
appearance  in  South  America  did  not  antedate  the  Santa  Cruz 
epoch,  whereas  Professor  Scott  points  out  that  they  also 
occur  in  the  oldest  known  Tertiary  and  possibly  even  pre- 
Tertiary  deposits  of  Patagonia,  and  that  there  is  every 
appearance  of  their  having  been  indigenous  in  that  region. 
It  is,  in  fact,  generally  assumed  now  that  South  America  was 
the  original  home  of  the  edentates.  If  it  is  correct,  as  I  have 
endeavoured  to  show,  that  Central  America  has  only  come  into 
existence  in  comparatively  recent  geological  times,  and  that 
the  whole  continent  of  South  America  in  the  dawn  of  the 
Tertiary  Era  consisted  of  several  distinct  masses,  Patagonia 

*  Woodward,  A.  Smith,  "  Grypotherium  listai,"  p.  64. 
t   Scott,  W.  B.,  "  Princeton  Expedition  to  Patagonia,"  Vol.  V.,  p  7. 
L.A.  D  D 


402  ORIGIN   OF   LIFE   IN   AMERICA 

at  that  time  must  have  had  a  direct  land  connection  with 
western  North  America  almost  independently  of  the  rest  of 
South  America  (Fig.  14).  At  a  still  earlier  stage  there  was 
even  a  more  marked  affinity  between  Patagonia  and  south- 
western North  America ;  and  from  this  Professor  Osborn  con- 
cluded that  the  northern  and  southern  continents  were  con- 
nected by  land.  But  the  points  of  resemblance  are  not  alone 
with  Patagonia  and  south-western  North  America.  Professor 
Gaudry  *  expressed  his  astonishment  at  the  striking  faunistic 
relationship  between  the  Patagonian  Notostylops  fauna  on  the 
one  hand,  and  the  faunas  of  the  Torrejon  in  New  Mexico  and 
Cerney  in  France  on  the  other.  That  a  land  bridge,  discon- 
nected at  certain  intervals,  extended  between  western  North 
America  and  southern  Europe  I  have  urged  again  and  again 
in  the  preceding  chapters ;  and  it  should  be  borne  in  mind 
how,  even  in  these  remote  times,  special  facilities  existed  for 
the  passage  of  species  from  Europe  to  the  extreme  south  of 
South  America,  which  no  doubt  were  taken  advantage  of  by 
several  groups  then  inhabiting  the  Old  World. 

Until  recently  it  was  thought  that  North  and  South  America 
could  have  had  no  land  connection  subsequently  to  these  early 
events  until  the  end  of  the  Miocene  or  the  beginning  of  the 
Pliocene  Periods.  Professor  Osborn,  f  however,  has  shown 
that  there  is  now  evidence  for  the  existence  of  true  edentates 
of  the  Megalonyx  type  in  the  Mascall  beds  of  Oregon,  which 
are  of  Middle  Miocene  age.  During  the  Miocene  Period 
Central  America  in  its  present  shape  had  not  yet  come  into 
existence.  Hence  we  may  assume  that  even  in  Miocene  times 
there  was  a  land  connection  between  western  North  America 
and  some  portion  of  South  America  by  means  of  a  route 
which,  as  I  argued,  lay  to  the  west  of  that  continent. 

The  rodents  of  the  Santa  Cruz  fauna,  as  previously  men- 
tioned, all  belong  to  the  section  Hystricomorpha.  They  are 
very  closely  allied,  according  to  Professor  Scott,  to  recent 
South  American  genera.  Yet  all  are  extinct  and  many  of 
them  have  left  no  successors.  Nevertheless,  though  the  Santa 
Cruz  rodents  are  more  primitive,  the  skull  structure  is  nearly 

*  Gaudry,  A.,  "  Fossiles  de  Patagonie,"  p.  105. 
t  Osborn,  H.  F.,  "  The  Age  of  Mammals,"  p.  289, 


FOSSIL   RODENTS  403 

the  same  as  in  the  recent  ones.  There  is  reason  to  believe, 
says  Professor  Scott,*  that  several  of  the  genera  represent 
the  direct  ancestors  of  existing  forms.  Viscacha  was  probably 
derived  from  Prolagostomus,  Dolichotis  from  Schistomys, 
Erethizon  and  Coendu  from  Steiromys.  As  regards  the  latter, 
it  is  interesting  to  note  that  it  resembles  the  recent  Erethizon 
more  than  it  does  the  modern  South  American  genera 
of  the  same  family.  It  seems  to  me  probable,  therefore, 
as  I  have  already  suggested  (pp.  69 — 71),  that  the  South 
American  and  North  American  tree  porcupines  originated 
from  two  distinct  branches  of  ancestral  Steiromys-like  rodents, 
thus  favouring  the  view  I  advocated  of  a  direct  land  connec- 
tion between  Patagonia  and  south-western  North  America. 
That  the  genus  Erethizon,  to  which  all  the  North  American 
porcupines  belong,  should  not  be  known  from  pre-Pleistocene 
deposits  presents,  no  doubt,  a  difficulty  to  the  acceptance  of 
this  theory,  but  its  ancestors  may  have  remained  on  the  last 
remnants  of  the  land  which  once  existed  westward  of  North 
and  South  America  until  compelled  to  leave  that  land  in  Plio- 
cene times,  when  it  finally  subsided. 

The  Santa  Cruz  fauna  likewise  reveals  an  affinity  with  the 
fauna  of  Australia  and  Tasmania.  The  Patagonian  marsupials 
are  referable  to  three  families,  remnants  of  which  survive  in 
widely  separated  parts  of  the  world.  The  Thylacinidae,  now 
confined  to  Tasmania,  where  the  Tasmanian  wolf  represents 
the  family,  formerly  inhabited  both  Patagonia  and  Australia. 
As  we  might  expect,  the  Santa  Cruz  thylacines  are  of  a  more 
primitive  type  than  the  Tasmanian  wolf,  but  Professor  Sinclair 
expects  that  the  common  ancestor  of  these  two  will  probably 
be  found  among  the  marsupials  occurring  in  still  older  Pata- 
gonian deposits.  The  opossums  (Didelphyidae),  among  which 
Microbiotherium  is  the  best  known,  are  met  with  in  several 
genera  in  the  Santa  Cruz  beds.  The  Cretaceous  Proteo- 
didelphys  suggests,  as  I  have  already  mentioned,  that  South 
America  must  be  looked  upon  as  the  original  home  of  the 
family  whence  some  members  passed  into  North  America  and 
Europe.  I  have  briefly  alluded  to  the  occurrence  in  Ecuador 

' 

*  Scott,  W.  B.,  "Princeton  Expedition,"  Vol.  V.,  pp.  384—386  and 
p.  413. 

D  D  2 


404  ORIGIN  OF  LIFE   IN  AMERICA 

of  the  marsupial  Caenolestes  and  to  its  being  the  only  living 
member  of  the  extinct  family  Epanorthidae.  In  the  Santa 
Cruz  beds  this  and  another  family  of  herbivorous  marsupials 
are  represented  by  several  genera.  Professor  Sinclair  *  in- 
clines to  the  belief  that  the  South  American  Epanorthidae  and 
the  Australian  phalangers  have  had  common  ancestors.  From 
all  these  facts  he  concludes  that  a  land  connection  between 
Patagonia  and  the  Australian  region  must  have  existed  not 
later  than  the  close  of  the  Cretaceous  Period  or  the  beginning 
of  the  Tertiary  Era,  and  that  the  interchange  of  marsupials 
may  have  been  effected  between  the  two  continents  at  this 
time. 

Of  all  the  similarities  between  the  South  American  and 
Australian  extinct  faunas  none  perhaps  is  more  striking,  re- 
marks Dr.  Smith  Woodward,f  than  the  essential  identity  of 
the  extinct  Miolania  in  the  two  regions.  He  thinks  there  can 
be  no  doubt  that  this  creature  was  a  truly  terrestrial  or  marsh 
chelonian.  The  theory  of  a  former  land  connection  between 
South  America  and  Australia  see  mis,  therefore,  to  receive 
weighty  support  from  the  new  discovery  of  this  curious 
reptile. 

It  has  also  been  urged  that  the  Patagonian  fossil  fauna 
indicates  traces  of  an  affinity  with  South  Africa.  Professor 
Scott, J  with  some  hesitation,  expresses  the  opinion  that  the 
resemblance  of  the  solitary  Patagonian  insectivore  Necrolestes 
to  the  golden  mole  Chrysochloris  of  South  Africa  may  be  due 
to  genetic  relationship.  It  is  significant,  in  view  of  the  early 
Tertiary  faunistic  relationship  of  Patagonia  and  western 
North  America,  to  note  that  certain  creatures  resembling  the 
golden  moles  made  their  appearance  in  North  America  in 
Oligocene  and  Lower  Miocene  times.  I  have  had  occasion  to 
allude  to  Xenotherium  and  Arctoryctes  already  (p.  246).  The 
affinities  between  these  various  forms  are  not  very  marked.  At 
any  rate,  it  would  be  unsafe  to  draw  any  conclusions  as  to  the 
existence  of  a  former  direct  land  bridge  between  Patagonia 
and  South  Africa  from  the  presence  of  Necrolestes  in  the 
Santa  Cruz  deposits. 

*  Sinclair,  W.  J.,  "  Marsupial  Fauna  of  Santa  Cruz,"  pp.  76—81. 
t   Woodward,  A.  Smith,, "Extinct  Eeptiles  from  Patagonia,"  p.  182. 
J  Scott,  W.  B.,  "  Princeton  Expedition,"  Vol.  V.,  p.  379. 


FAUNISTIC   AFFINITIES  405 

Professor  Tullberg's*  reference  to  a  pre-Tertiary  land 
bridge  between  South  America  and  south-west  Africa  is  not 
very  definite.  From  his  remarks  it  is  not  clear  that  he  is  in 
favour  of  the  existence  of  an  independent  connection  far  to 
the  south  of  the  one  I  discussed  in  the  last  chapter. 

These  are  among  the  more  important  results  derived  from 
the  study  of  the  fossil  fauna  of  Argentina  as  to  the  affinities 
presented  by  this  part  of  South  America  to  the  more  distant 
parts  of  the  world.  We  have  still  to  consider  the  faunistic 
kinship  between  Argentina  and  the  neighbouring  states  of 
South  America.  Dr.  von  Ihering  f  pointed  out  long  ago  that, 
whereas  America  as  a  whole  is  the  richest  part  of  the  world 
in  the  variety  of  genera  and  species  of  fresh-water  mussels, 
Chile  and  Peru  belong  to  the  poorest  districts,  since,  at  any 
rate  west  of  the  Andes,  only  the  genus  Unio  occurs.  Similarly 
Ampullaria  and  many  other  typically  American  fresh-water 
genera  are  absent  from  Chile.  On  the  other  hand,  the  Unios  of 
Chile  are  most  of  them  nearly  related  to  those  of  the  La  Plata 
region.  Dr.  von  Ihering  J  concludes  from  these  very  peculiar 
zoographical  features  that,  while  the  whole  of  southern  South 
America  ( Archiplata)  formed  a  united  land-mass  in  Secondary 
times,  the  elevation  of  the  Andes  afterwards  prevented  a 
faunistic  interchange  between  the  two  districts.  The  fresh- 
water Crustacea  tell  us  a  very  similar  story.  The  fresh-water 
crayfish  Parastacus  is  met  with  in  eight  species  in  South 
America.  §  None  of  them  occur  north  of  southern  Brazil, 
although  several  ,of  the  Chilean  species  are  closely  related  to 
Brazilian  ones.  The  fresh-water  crab  Aeglea  laevis,  no  doubt 
an  exceedingly  ancient  form  and  the  only  representative  of  the 
family  Aegleidae,  lives  in  identically  the  same  species  on  both 
sides  of  the  Andes.  The  absence  of  almost  all  the  leading 
genera  of  Brazilian  fishes  from  Chile  and  Patagonia,  ||  empha- 
sises the  noteworthy  distinctness  in  the  fresh-water  fauna  of 
the  two  regions.  On  the  other  hand,  Patagonia  and  Chile 
present  traces  of  a  relationship,  as  I  intend  to  show  later  on, 

*  Tullberg,  Tycho,  "  System  der  Nagetiere,"  p.  495. 

t  Ihering,  H.  von,  *'  Verbreitung  der  Ampullarien,"  p.  106. 

t  Ihering,  H.  von,  "  Archhelenis  and  Archinotis,"  p.  57. 

§   Ortmann,  A.  E.,  "Distribution  of  Decapods,"  pp.  292—296. 

||  Eigenmann,  C.,  "Freshwater  Fishes  of  Patagonia,"  pp.  227—229. 


406  OBIGIN   OF   LIFE   IN  AMERICA 

with  western  North  America,  with  southern  Africa  and  with 
New  Zealand  and  Australia. 

As  we  ascend  the  Andes  from  northern  Argentina,  we  meet 
with  a  familiar  animal  which  we  generally  associate  with  Peru 
and  its  inhabitants,  namely,  the  llama.  The  llama  is  only  a 
domestic  animal.  But  its  wild  ancestor  the  huanaco  (Lama 
huanachus)  still  exists  plentifully  in  the  Andes  of  Peru  and 
Chile,  as  well  as  in  the  plains  of  Patagonia.  Its  western  dis- 
tribution, like  that  of  the  bear,  some  of  the  deer  and  many 
vertebrates  and  invertebrates,  is  thus  very  marked  and  de- 
mands an  explanation.  For  the  benefit  of  those  who  may 
be  unacquainted  with  the  pedigree  of  this  creature  I  may  men- 
tion that  the  huanaco  and  its  domesticated  relations  the  llama 
and  alpaca,  are  essentially  camels  in  structure.  There  are 
certain  differences  in  the  teeth,  the  huanaco  being  with- 
out a  hump  and  smaller  than  the  camel,  while  the  head  is 
more  like  that  of  a  sheep.  But  the  shape  and  structure  of  the 
skull  and  bones  and  the  general  anatomy  are  very  similar 
in  the  huanaco  and  camel,  implying  that  they  have  descended 
from  the  same  ancestor.  The  occurrence  of  the  camels  in  Asia 
and  of  the  llamas  in  South  America  is  a  case  of  widely  dis- 
continuous distribution  of  two  related  genera  and  thus  points 
to  an  ancient  origin.  The  geological  history  of  the  family  is 
of  the  greatest  interest.  The  first  member  of  the  camel  tribe 
makes  its  appearance  in  Argentina  in  a  deposit  known  as  the 
Lower  Pampean,  which  Dr.  Ameghino  considers  of  Pliocene 
age,  though  some  authorities  think  it  is  more  recent.  Here 
occurs  Palaeolama,  an  extinct  ancestor  of  the  huanaco.  In 
the  upper  portions  of  the  same  deposit  the  remains  of  quite 
a  number  of  llama-like  creatures  have  been  discovered  such 
as  Protauchenia,  Hemiauchenia,  Stilauchenia  and  Mesolama, 
as  well  as  the  huanaco  itself.  That  is  about  all  we  know  of  the 
past  history  of  these  camel -like  animals  of  South  America. 
The  fact  that  no  members  of  the  family  are  known  from  earlier 
deposits  than  Pliocene,  and  that  the  extinct  genera  are  nearly 
related  to  the  living  one,  suggests  that  the  ancestors  of  the 
huanaco  were  not  originally  native  to  South  America  but  in- 
vaded the  continent  from  elsewhere.  Africa  and  Europe  no 
longer  were  connected  with  South  America.  North  America 
is  thus  the  only  possible  source  whence  the  ancestral  huanacos 


THE   LLAMA  AND   ITS  PAST  HISTOBY       407 

or  llamas  could  have  originated.  And  that  is  precisely  what 
happened,  as  already  mentioned  (p.  86).  Towards  the 
latter  end  of  the  Eocene  Period  there  appeared  four  genera 
in  western  North  America,  all  of  which  exhibit  decidedly 
camel -like  characters,  and  Professor  Osborn  *  believes  that 
one  of  these,  the  diminutive  Protylopus,  may  possibly  repre- 
sent the  most  remote  ancestor  of  the  grand  American  phylum 
of  camels.  Other  genera  occur  in  Oligocene  and  Miocene  beds 
of  North  America.  During  the  latter  period  camels  had  ap- 
parently spread  in  great  herds  over  the  continent.  It  is 
thus  probable  that  they  then  extended  their  range  to  other 
parts  of  the  world.  Some  of  them,  like  Pliauchenia,  had 
assumed  llama-like  characters,  and  as  the  .western  Pacific  land- 
belt  was  then  in  communication  with  California  the  ances- 
tors of  the  South  American  llamas  were  able  to  pass  south- 
ward. According  to  Professor  Osborn  llamas  survived  in 
North  America  until  Pleistocene  times.  They  were  then 
becoming  extinct  in  the  eastern  States,  lingering  on  in  Cali- 
fornia where  the  great  sabre -tooth  tiger  no  doubt  stalked  tihem. 
In  the  Siwalik  beds  of  northern  India  camels  first  appear  in 
the  Pliocene,  as  in  South  America,  and  it  is  generally  assumed 
that  the  ancestors  of  the  Old  World  camels  crossed  over  to 
Asia  by  the  Bering  Strait  land  bridge.  But  as  it  was  probably 
in  Miocene  times  that  these  early  camels  wandered  westward 
from  North  America,  the  Bering  Strait  land  bridge  had  not 
yet  come  into  existence.  They  must  have  utilised  the  more 
southern  bridge,  which  I  think  replaced  it  in  earlier  Tertiary 
times  (Fig.  16). 

Kecently  we  have  received  clear  proof  of  a  migration  of 
mammals  from  Asia  to  North  America,  which  I  think  must 
have  taken  place  across  the  same  Pacific  land  bridge.  One 
of  the  most  remarkable  discoveries  among  the  many  note- 
worthy ones  in  North  American  palaeontology  is  that  by  Dr. 
Matthew  and  Mr.  Cookf  of  Asiatic  antelope  remains  in 
western  Nebraska.  The  American  invasion  by  true  Asiatic 
antelopes  was  brilliantly  and  amply  confirmed,  according  to 
Professor  Osborn,  by  Mr.  Merriam's  discovery  in  Nevada, 

*  Osborn,  H.'  F.,  "  Age  of  Mammals,"  p.  170. 

t  Matthew,  W.  D.,  and  H.  J.  Cook,  "  Pliocene  Fauna  from  Nebraska." 


408  ORIGIN   OF   LIFE  jIN   AMERICA 

Rather  earlier  arrived  in  North  America  the  mastodons, 
and  no  doubt  by  the  same  Pacific  land  connection.  They  in- 
vaded the  continent  from  Asia  and  remained  until  Pleistocene 
times,  being  thus  co-existent  with  the  early  races  of  man  in 
America.  That  they  travelled  beyond  North  America,  pene- 
trating far  into  the  southern  continent,  has  been  clearly  de- 
monstrated. A  large  number  of  apparently  distinct  forms  have 
been  described  from  South  America,  most  of  them,  as  we 
should  expect,  from  the  west  coast,  though  it  is  very  doubtful 
if  more  than  a  few  species  lived  there.  Dr.  Nordenskiold 
thinks  that  Mastodon  chilensis,  M.  bolivianus  and  M.  andium 
all  belong  to  one  species.  In  North  America,  as  in  Europe, 
both  the  trilophodont  and  tetralophodont  types  of  mastodon 
have  been  discovered,  that  is  to  say,  animals  which  possessed 
intermediate  molar  teeth  with  either  three  or  four  ridges. 
In  the  South  American  Mastodon  andium,  at  any  rate,  the 
molars  are  in  the  transition  stage  between  the  trilophodont 
and  tetralophodont  types.  These  extinct  elephants  made  their 
first  appearance  in  Argentina  in  the  Lower  Pampean  deposits. 
Since  they  had  thus  penetrated  so  far  south  in  early  Pliocene 
times  they  must  have  left  North  America  before  Central 
America  had  come  into  existence.  They  could  only  have 
wandered  southward  along  the  southern  continuation  of  the 
Pacific  land  bridge  and  have  entered  the  South  American 
continent  from  the  west  during  the  time  the  bridge  was  joined 
to  the  latter.  Dr.  Nordenskiold  *  argues  that,  having  no  more 
efficient  competitors  in  South  America,  the  mastodon  probably 
lived  longer  there  than  in  North  America. 

Hitherto  the  theory  has  been  quite  generally  accepted  that 
the  invasions  of  animals  from  North  America  to  the  southern 
continent,  during  later  Tertiary  and  Pleistocene  times,  took 
place  across  the  narrow  isthmus  of  Central  America  as  soon 
as  its  formation  was  completed.  Some  doubts  have  latterly 
been  raised  as  to  the  nature  of  the  barrier  which  prevented 
the  interchange  of  the  two  faunas  in  the  earlier  portion  of 
the  Tertiary  Era.  Yet  until  the  discovery  of  gravigrade  sloth 
remains  in  the  Miocene  Mascall  beds  of  Oregon  was  announced 
by  Professor  Sinclair,  the  assumption  seemed  perfectly  justi- 

*  Nordenskiold  E.,  "  Saugetier-fossilien  des  Tarija  Tals,"  pp.  14—25. 


RANGE   OF   FOSSIL  ELEPHANTS  409 

fied,  from  all  available  data,  that  North  and  South  America 
became  joined  at  the  commencement  of  the  Pliocene  Period. 
It  was  supposed  that  the  advance  of  northern  types,  such  as 
the  mastodon  and  hosts  of  others,  towards  the  southern  con- 
tinent must  have  coincided  with  the  opening  up  of  the  new 
land  of  Central  America.  The  occurrence  of  edentate  remains 
in  North  American  Miocene  deposits  upsets  this  theory, 
because,  if  mammals  were  able  to  reach  North  America  from 
the  south  during  the  Miocene  Period,  northern  species  must 
have  had  equal  facilities  for  invading  South  America  at  this 
time.  If  there  is  geological  evidence  that  Central  America  was 
not  available  as  a  safe  land  bridge  between  North  and  South 
America  in  Miocene  times,  some  other  land  connection 
must  have  united  the  two  continents.  When  I  advanced  the 
theory  of  the  former  existence  of  a  Pacific  land  bridge  between 
North  and  South  America,  westward  of  Central  America,*  I 
was  unaware  of  Professor  Sinclair's  interesting  discovery 
among  the  Mas  call  beds  of  Oregon.  My  theory  was  largely 
founded  on  zoogeographical  data — on  curious  instances  of 
discontinuous  distribution  of  ancient  groups  in  North  and 
South  America.  Professor  Osborn  f  regards  my  theory  as 
inconsistent  with  the  fact  that  the  Pacific  land  bridge  should 
only  have  been  used  by  these  gravigrade  sloths.  If  such  a 
land  connection  really  existed  why  was  it  not  more  exten- 
sively used  ?  I  think  it  was  used  by  other  animals,  such  as  the 
mastodons  and  the  ancestors  of  the  llamas  to  pass  southward, 
and  by  the  ancestors  of  the  North  American  tree  porcupines 
in  entering  North  America. 

Since  I  wrote  my  essay  on  the  problem  of  a  former  land 
connection,  other  than  the  Central  American  one,  between 
North  and  South  America,  I  have  had  opportunities  of  study- 
ing the  subject  more  at  my  leisure.  I  find  that  the  affinity 
existing  between  south-western  North  America  and  the 
extreme  south  of  South  America  among  some  of  the  more 
ancient  groups  of  animals  is  greater  than  I  thought.  Let 
us  examine  this  curious  relationship  between  the  two 
widely  separated  faunas  a  little  more  closely.  I  explained 

*  Scharff,  E.  F.,  "  Early  Tertiary  Land-connection." 
t  Osborn,  H.  F.,  "Age  of  Mammals,"  p.  292. 


410  ORIGIN   OF  LIFE   IN  AMERICA 

(p.  120)  that  the  mammals  inhabiting  Patagonia  and  south- 
western North  America  in  late  Mesozoic  and  early  Tertiary 
times  indicated  the  existence  of  a  direct  land  bridge  between 
these  two  areas.  But  the  Patagonian  land-mass  must  have 
included  Chile  or  such  parts  of  it  as  were  then  above  sea- 
level.  We  know  very  little  of  the  past  fauna  of  Chile.  It', 
as  I  endeavour  to  prove,  a  portion  of  our  living  fauna  is  of 
great  antiquity,  some  animals  should  reveal  unmistakable 
signs  of  this  early  affinity  of  Chile  with  that  of  south-western 
North  America.  I  imagine,  as  previously  stated,  that  the  early 
Tertiary  land  bridge  connected  Chile  directly  with  western 
Mexico  and  California.  Hence  we  might  expect  that  not  only 
Chile  and  Patagonia,  but  the  outlying  islands  of  California, 
as  well  as  the  Galapagos  islands,  ought  to  show  a  faunistic 
relationship  with  one  another. 

I  have  already  alluded  to  the  fact  that  three  groups  of  the 
snail  Bulimulus  inhabiting  Chile  and  Peru,  the  Galapagos 
islands  and  Lower  California  are  very  similar  in  their  narrow 
elongated  shape,  so  that  they  were  formerly  considered  to  be 
very  closely  related.  Dr.  Pilsbry*  is  now  of  opinion  that  this 
similarity  in  appearance  is  not  any  evidence  of  near  relation- 
ship but  a  special  parallel  modification  of  different  Bulimulus 
stocks,  or,  as  we  might  say,  a  case  of  convergence.  He  attri- 
butes these  cases  to  be  products  of  similar  environments.  Yet 
is  the  environment  of  Chile  really  so  similar  to  that  of  the 
Galapagos  islands  or  Lower  California  ?  Climatically  and  geo- 
logically I  should  think  there  must  be  a  good  deal  of  difference 
between  these  districts. 

The  relationship  between  the  western  North  American  snail 
fauna  and  that  of  western  and  south-western  South  America 
is  well  illustrated  by  the  distribution  of  the  genus  Epi- 
phragmophora.  This  is  a  group  of  snails  entirely  confined  to 
Central  America  and  the  Pacific  borders  of  North  and  South 
America.  It  is  important  to  note  also  that  the  majority  of 
the  snails  inhabiting  the  islands  off  the  coast  of  California 
belong  to  this  genus.  Cerros,  Guadelupe,  Santa  Barbara, 
San  Clemente  and  other  islands  all  have  their  peculiar  species 
of  Epiphragmophora.  Now  the  most  interesting  point  about 

*  Pilsbry,  H.  A.,  "Manual  of  Conchology  (Pulmonata),"  X.,  p.  126. 


'ANCIENT  LAND  CONNECTIONS  411 

the  members  of  this  genus  is  their  astonishing  resemblance, 
as  mentioned  before,  to  certain  species  of  the  European  group 
Helicigona,  including  the  well-known  Arianta  arbustorum. 
Some  of  the  American  shells  are  externally  so  much  like  the 
latter  that  they  were  placed  into  the  same  genus  until  recently. 
Dr.  Pilsbry,*  however,  maintains  that  the  European  Heli- 
cigona  differ  anatomically  from  Epiphragmophora,  and  that 
the  two  should  be  placed  in  quite  distinct  groups.     Even  on 
anatomical  grounds  opinions  may  differ  very  radically,  for 
Dr.  von  Ihering  claims  that  the  American  Epiphragmophora 
and  the  members  of  the  group  Helicigona  are  genetically  con- 
nected.   After  careful  examinations  of  the  European  Arianta 
arbustorum  and  the  Argentine   Epiphragmophora   tucuma- 
nensis  he  could  perceive  no  noteworthy  anatomical  difference 
between  the  two,  and  placed  them  both  into  the  same  genus. 
If  Dr.  von  Ihering's  f  observations  are  correct,  this  is  another 
example  of  the  same  extraordinary  relationship  between  Euro- 
pean and  west  American  forms  that  I  have  had  occasion  to 
point  out  in  previous  chapters.     Occasionally  this  relation- 
ship manifests  itself  only  in  Europe  and  south-western  North 
America.    In  other  cases  it  exists  simply  between  European 
and  western  South  American  forms.     In  this  case  both  the 
American  western  centres  are  related  to  the  European  centre 
of   dispersal.      It    clearly  illustrates,  as  stated  before,  that 
Europe  was  once  joined  to  a  mid-Atlantic  land  bridge  which 
communicated  directly  with  a  belt  of  land  lying  to  the  west  of 
America.     On  the  disappearance  of  the  latter  many  of  the 
animals  inhabiting  that  belt  of  land  took  refuge  in  the  western 
parts  of  America  and  still  persist  there. 

Epiphragmophora,  all  the  same,  does  not  clearly  reveal  the 
special  affinity  that  exists  among  the  older  forms  of  animal 
life  of  south-western  North  America  and  southern  South 
America.  The  wingless  insects  known  as  "  bristle  tails  "(Thy- 
sanura)  are  generally  looked  upon  as  a  very  ancient  group. 
Among  these  the  genus  Japyx,  which  is  easily  recognisable 
by  its  forceps -like  tail -appendage,  has  a  noteworthy  distribu- 
tion. Japyx  solifugus  occurs  in  the  Mediterranean  region, 

*  Pilsbry,  H.  A.,  "Manual  of  Conchology  (Pulmonata),"  IX.,  p.  195. 
t  Ihering,  H.  von,  "  System  der  Heliciden,"  p.  422. 


412  ORIGIN  OF  LIFE  IN  AMERICA 

whence  it  has  spread  as  far  north  as  southern  Germany. 
Several  other  species  are  peculiar  to  southern  Europe  and 
Madeira.  One  Japyx  is  found  in  India.  Across  the  Atlantic 
Japyx  subterraneus  has  been  observed  in  the  Mammoth  Cave 
of  Kentucky,  while  a  second  species  (Japyx  saussurei)  inhabits 
only  Mexico  and  Chile.* 

The  curious  scorpion-like  Koenenia,  the  only  genus  of  the 
order  Palpigradi,  is  confined,  as  already  mentioned,  to 
southern  Europe,  Texas  and  Chile.  As  far  as  America  is 
concerned,  it  is  limited  in  its  range  to  the  two  regions  alluded 
to.  The  family  of  spiders,  Mecicobothriidae,  according  to 
Mr.  Pocock,f  occurs  only  in  the  western  States  of  North 
America  and  in  Argentina,  the  genus  Hexura  being  found  in 
the  former  and  Mecicobothrium  in  the  latter  part  of  America. 

The  ancestral  form  of  the  evidently  very  ancient  family  of 
earthworms,  Megascolecidae,  seems  to  be  Notiodrilus.  This 
genus  is  met  with  in  America  only  in  Mexico,  Guatemala, 
Chile,  Argentina,  Patagonia,  Tierra  del  Fuego  and  the  Falk- 
land islands,  while  another  genus,  namely,  Kerria,  inhabits 
Lower  California  and  southern  South  America,  being  absent 
from  the  intermediate  area.  The  slug  Philomycus  has  a  wide 
range  in  North  America,  occurring  in  Mexico,  Guatemala  and 
Costa  Rica,  and  then  turns  up  again  far  away  to  the  south 
in  Chile.  Similarly  the  salamander  Plethodon,  which  in  North 
America  inhabits  principally  the  western  States,  is  found  in 
a  single  district  in  South  America,  namely,  in  Argentina. 
There  are  a  large  number  of  similar  examples  among  such 
forms  of  insects  that  we  have  reason  to  believe  date  back 
to  at  least  early  Tertiary  times.  The  best  known  example,  per- 
haps, is  that  of  the  common  northern  genus  Carabus.  In 
Mexico  there  are  still  two  species.  Neither  in  Central 
America,  nor  in  northern  nor  .middle  South  America  has  it 
been  discovered,  while  in  Chile  and  Tierra  del  Fuego  there 
are  nine  species.  That  the  latter  are  now  considered  suffi- 
ciently distinct  to  be  placed  into  the  separate  genus  Cero- 
glossus  does  not  alter  the  fact  that  they  are  closely  related 
to  northern  Carabi,  whereas  they  have  no  affinity  at  all  with 

*  Karsch.  F.,  "Neue  Fundorte  von  Japyx,"  p.  154. 

t  Pocock,  R.  I.,  "  Geographical  Distribution  of  Spiders,"  p.  346. 


CHILE   AND   CALIFOKNIA  413 

any  South  American  forms.  The  genus  of  Tenebrionidae 
Apocrypha  is  quite  confined  to  California  and  Chile.  That 
all  these  instances  indicate  the  existence  of  a  former  direct 
land  connection  between  Chile  and  California,  independent 
of  the  rest  of  South  America,  as  I  have  explained  before,  is 
indicated  by  another  example  derived  from  the  same  family 
of  beetles.  The  three  closely  allied  genera  Arthrocomus, 
Stomion  and  Eurymetopon  occur  respectively  in  Chile,  the 
Galapagos  islands  and  California. 

Under  this  heading  also  comes  an  instance  of  distribution 
which  had  not  hitherto  been  noted  and  which  was  pointed  out 
by  Mr.  McLachlan.*  He  remarked  that  the  family  Limno- 
philidae,  a  family  of  insects  the  larvae  of  which  manufacture 
those  cases  of  twigs  and  straws,  so  abundant  in  northern 
ponds  and  ditches,  is  not  known  to  occur  south  of  Mexico, 
except  in  Chile  and  the  Falkland  islands. 

It  was  Dr.  Wallace,f  I  believe,  who  first  drew  attention, 
as  already  noted  in  a  previous  chapter  (p.  235),  to  the 
remarkable  fact  that  a  large  number  of  European  and  North 
American  genera,  such  as  the  butterfly  Argynnis  and  the 
running  beetle  Carabus,  reappeared  far  south  of  the  tropics 
in  Chile,  Argentina  and  Tierra  del  Fuego.  I  also  alluded 
to  his  explanation  of  the  manner  in  which  this  surprising 
phenomenon  had  been  brought  about.  He  was  under  the  im- 
pression that  this  migration  across  the  tropics  had  been 
effected  mainly  during  successive  Glacial  Epochs,  when  the 
mountain  range  of  the  isthmus  of  Panama,  if  moderately  in- 
creased in  height,  might  have  become  adapted  for  the  passage 
of  northern  forms,  while  storms  would  often  carry  insects 
from  peak  to  peak  over  intervening  forest  lowlands  or  narrow 
straits  of  sea.  Improbable  as  this  theory  may  appear,  it  might 
still  be  defended  as  long  as  we  had  to  deal  merely  with  the 
occurrence  in  southern  South  America  of  a  few  northern 
insects.  But  the  phenomenon  is,  as  we  have  seen,  a  much 
more  widespread  one.  It  applies  to  earthworms,  slugs,  sala- 
manders and  even  mammals,  and  it  is  evidently  the  result 
of  a  dispersal  which  occurred  long  before  the  Glacial  Epoch. 

*  McLachlan,  E.,  "Insect  Fauna  of  Chile,"  p.  162. 

f  Wallace,  A.  E.,  "  Geographical  Distribution,"  Vol.  II.,  p.  45. 


414  ORIGIN   OF   LIFE   IN   AMERICA 

It  took  place,  in  fact,  in  very  remote  times,  probably  during 
the  dawn  of  the  Tertiary  Era;  and  only  such  forms  as  were 
capable  of  preserving  their  specific  and  generic  characters 
till  the  present  day  clearly  reveal  their  northern  origin. 

The  flora  of  the  New  World,  as  I  remarked  in  the  paper 
just  referred  to,  retains  even  more  pronounced  traces  of  that 
curious  relationship  between  the  south-western  areas  of  its 
two  continents.*  As  among  the  fossil  mammals  so  do  we 
find  also  among  the  fossil  plants,  a  remarkable  affinity  in  late 
Mesozoic  deposits  between  species  from  Argentina  and  from 
western  North  America.  •  Professor  Berry  tells  us  that  in 
mid-Cretaceous  times  seventy-five  per  cent,  of  the  known 
plants  of  Argentina  were  characteristic  types  of  the  Dakota- 
group  flora  of  North  America.  During  a  period  of  geological 
history  when  a  large  section  of  the  existing  western  part  of 
South  America  was  under  water,  there  was  this  extraordinary 
similarity  between  two  regions  lying  at  such  a  great  distance 
from  one  another.  Professor  Berry  justly  argues  that  the 
surprising  affinity  of  these  floras  to  one  another  points  to  a 
community  of  origin.  In  these  ancient  plant  deposits  of 
Argentina  ,all  the  familiar  northern  genera  such  as  Lirio 
dendron,  Liquidambar,  Cinnamomum  and  Sassafras  are  met 
with.  Even  Platanus,  Populus,  Quercus  and  other  modern 
genera  are  represented.  No  wonder  that  Professor  Berry  f 
came  to  the  conclusion  that  a  geographical  connection  must 
have  existed  between  North  and  South  America  during  mid- 
Cretaceous  times.  During  Cretaceous  and  early  Tertiary 
times  the  genus  Sequoia,  to  which  the  Californian  red-wood 
and  big-trees  belong,  likewise  ranged  from  North  America  to 
Chile.  And  it  is  now  held  by  many  botanists  that  the  fossil 
Sequoia  langsdorfi  is  identical  with  the  still  living  big-tree 
(Sequoia  gigantea)  of  California.  We  possess  no  fossil  testi- 
mony of  the  occurrence  of  the  smaller  deciduous  plants  in 
those  remote  times,  but  to  judge  from  the  fact  that  many  of 
the  Mesozoic  genera  of  trees  still  survive  to  the  present  day, 
certain  persistent  deciduous  species  presumably  did  so  too. 
Mr.  Engelhardt  J  records  a  number  of  plant  remains  from  the 

*  Scharff,  E.  F.,  "  Early  Tertiary  Land-connection,"  pp.  523—526. 
f  Berry,  E.  W.,  "  Mid- Cretaceous  Geography,"  p.  510. 
I  Engelhardt,  H.,  "  Tertiarpflanzen  von  Chile,"  p.  635. 


FOSSIL   PLANTS   OF   ARGENTINA  415 

west  coast  of  Chile  which  he  considers  to  be  of  early  Tertiary 
age.  Of  these  the  greater  portion,  he  thinks,  belongs  to  still 
existing  species,  though  he  hesitates,  in  the  absence  of  further 
evidence,  to  adopt  the  recent  specific  names.  At  any  rate, 
almost  all  are  very  closely  related  to  species  now  living  in 
the  West  Indies,  Central  America  and  Brazil. 

There  exists  a  very  widespread  assumption  that  no  species 
of  animals  or  plants  survive  to  this  day  from  the  Mesozoic 
Era.  As  our  knowledge  of  fossil  animals  increases,  instances 
accumulate  of  very  close  resemblance  of  Mesozoic  species  of 
mollusks  to  those  now  living,  while  some  genera  certainly 
date  back  to  Palaeozoic  times,  so  that  we  can  no  longer  place 
implicit  faith  in  the  old  traditional  belief.  My  own  convic- 
tion is  that  many  species  of  the  less  highly  organised  groups 
of  animals  have  survived  unchanged  even  from  those  remote 
times  to  the  present  day.  We  know  that  certain  species  of 
plants  such  as  Sequoia  langsdorfi,  and  some  of  the  Unios 
among  animals,  have  remained  practically  unaltered  through- 
out a  series  of  geological  ages.  It  seems  equally  possible 
that  others  of  whose  geological  history  we  know  nothing  have 
likewise  done  so. 

Professor  Asa  Gray  and  Sir  Joseph  Hooker  *  long  ago 
directed  attention  to  the  unexpected  feature  that  many  genera, 
and  even  species  of  North  American  plants,  recur  in  the  dis- 
tant regions  of  southern  South  America.  More  recently 
Professors  Engler,f  Bray  and  Hackel  have  dwelt  on  this  re- 
markable phenomenon,  and  have  speculated  on  the  problems 
connected  with  it.  The  flora  of  the  Rocky  Mountains, 
including  the  Sierra  Nevada  Mountains  above  the  transition 
zone,  and  the  mountains  of  Chile  and  Argentina,  though 
separated  from  one  another  by  a  stretch  of  some  ten  degrees  of 
latitude  of  moist  tropical  country,  abound  in  northern  genera 
of  plants,  such  as  Ranunculus,  Anemone,  Geranium,  Spiraea, 
Geum,  Rubus,  Saxifraga,  Vaccinium,  Gentiana,  Hieracium 
and  others.  The  greater  number  of  such  plants  occurring  in 
the  southern  continent  are  endemic,  pointing  to  long -con- 
tinued isolation.  Yet  certain  species  even  of  the  Rocky 

*  Gray,  Asa,  and  J.  Hooker,  "Vegetation  des  Eocky  Mountain  Ge- 
bietes,"  p.  292. 

t  Engler,  A.,  "  Entwicklungsgeschichte  der  Florengebiete,"  .II.,  p.  2«*>6. 


416  ORIGIN   OF   LIFE   IN   AMERICA 

Mountain  arctic  alpine  region  reappear  in  the  extra-tropical 
Andes,  being,  so  far  as  is  known,  wholly  absent  from  the 
Mexican  Mountains  as  well  as  from  the  tropical  Andes. 
Among  these  Professor  Bray  mentions  particularly  Gentiana 
prostrata,  Trisetum  subspicatum,  Primula  farinosa  and  its 
variety  magellanica,  Draba  incana,  Alopecurus  alpinus,  Saxi- 
fraga  caespitosa,  Polemonium  microcanthum  and  Collomia 
gracilis.  Dr.  Stapf  kindly  drew  my  attention  to  another 
instance,  namely,  to  the  occurrence  on  the  mountains  of 
Argentina,  at  a  height  of  10,000  feet,  of  the  typically  arctic 
genus  of  grasses  Phippsia.  The  similarity  in  the  flora  of  the 
two  regions  is  by  no  means  confined  to  mountain  forms. 
Some  species  of  the  western  plains  of  North  America  also 
reappear  in  the  extreme  south  of  South  America.  Thus  the 
monotypical  saxifrage  Lepuropetalon,  a  peculiar  and  some- 
what abnormal  genus,  grows  in  damp  low-lying  meadows  in 
Texas.  Yet  far  south  on  the  coast  of  Chile  the  same  species, 
Lepuropetalon  spathulatum  is  to  be  met  with. 

A  few  of  these  plants  may  possibly  have  been  casually  in- 
troduced from  the  northern  locality  to  the  southern.  But  in 
most  cases,  Professor  Bray  *  thinks,  we  have  to  deal  with 
forms  which  were  connected  by  a  remote  ancestry,  and  which 
flourished  at  a  time  and  under  conditions  permitting  a  more 
general  distribution. 

What  these  conditions  were  like  he  does  not  venture  to  sug- 
gest, but  a  direct  land  bridge  between  western  North  America 
and  Chile  probably  existed,  as  I  suggested,  in  late  Cretaceous 
and  early  Tertiary  times.  To  it,  I  think,  the  relationship 
of  the  floras  of  these  two  widely  separated  areas  to  one 
another,  is  mostly  due.  Whether  many  species  of  plants 
have  persisted  to  the  present  day  from  such  remote  times 
we  do  not  know.  Some  no  doubt  have,  and,  as  already 
stated,  others,  among  them  those  alluded  to,  may  have 
done  so.  A  large  portion  of  this  old  western  land,  with' 
its  mixture  of  a  southern  and  northern  fauna  and  flora, 
evidently  remained  above  sea-level  until  a  much  later  geo- 
logical period.  The  evidence  derived  from  certain  relict 
land -areas  of  this  Pacific  land  belt  clearly  shows  that  a 

*  Bray  W/L.,  "  Belations  of  North  American  Flora,"  pp.  709—716. 


FLORAL  AFFINITIES  417 

southern  flora  passed  over  them,  for  of  course  southern 
plants  penetrated  northward  just  as  animals  did.  Mr.  Sereno 
Watson,*  for  example,  in  referring  to  the  flora  of  the  small 
island  of  Guadalupe  off  the  west  coast  of  California,  remarks 
that  the  presence  of  so  many  South  American  types  suggests 
that  this,  and  the  similar  element  which  characterises  the 
flora  of  California,  may  be  due  to  some  other  connection  be- 
tween these  distant  regions  than  the  one  now  existing.  He 
expresses  the  opinion,  too,  that  all  the  peculiarities  in  the 
western  floras  of  both  continents  had  a  common  origin  in  an 
ancient  flora  which,  prevailed  over  a  wide,  now  submerged 
area,  and  of  whose  character  the  former  are  the  partial 
exponents. 

As  regards  'the  question  whether  the  northern  plants 
growing  in  Chile  and  Argentina  can  really  be  regarded  as 
indigenous  or  introduced,  Professor  Hackel  has  recently  dealt 
with  this  problem  from  a  new  point  of  view.  He  shows  that 
the  species  which  are  either  identical  with  European  or  North 
American  plants,  or  such  as  may  be  considered  as  varieties  or 
sub-species  of  them,  increase  rather  than  diminish  as  we  go 
further  south.  Thus  he  records  fifty-one  plants  from 
southern  Patagonia  and  Tierra  del  Fuego  belonging  to  this 
group,  which  he  regards  as  undoubtedly  indigenous  to  these 
countries.  Thirty  others  may  possibly  have  been  introduced 
by  man.  Professor  Hackel  thinks  that  their  southward 
advance  could  only  have  taken  place  step  by  step  on  a  land 
surface.  If  these  plants  had  passed  across  Central  America 
and  along  the  Andes,  we  should  find  relict  colonies  of  the 
species,  or  at  least  their  modified  descendants,  scattered  on 
their  route  of  migration.  Only  very  few  of  such  occur  in 
Bolivia,  Peru  and  Ecuador,  and  these  have  the  appearance 
of  having  reached  these  localities  from  the  south  rather  than 
from  the  north.  When  we  examine  the  composition  of  this 
remarkable  flora  in  the  Magellan  district,  we  notice,  according 
to  Professor  Hackel,f  that  the  majority  of  the  species  belong 
to  the  grasses  (Gramineae)  and  the  sedges  (Cyperaceae).  The 
dicotyledons  only  comprise  fifteen  species.  This  he  believes 

*  Watson,  Sereno,  "  Flora  of  Guadalupe  Island,"  p.  112. 
t  Hackel,  E.,  "  Flora  der  Magellanslander,"  pp.  cxi — cxv. 
L.A.  E  B 


418  ORIGIN  OF  LIFE   IN   AMERICA 

to  be  due  to  the  greater  antiquity  of  the  grasses  and  sedges, 
and  he  argues  in  favour  of  an  ancient  direct  land  connection, 
long  since  disappeared,  on  which  the  slow  southward  advance 
of  these  forms  took  place,  the  identical  species  having  pre- 
served their  specific  characters  throughout  a  long  series  of 
ages.  This  is  precisely  the  conclusion  I  have  come  to  in 
regard  to  many  species  of  animals  of  very  wide  range,  con- 
trary to  the  view  generally  held  that  most  of  such  forms  are 
to  be  regarded  as  human  importations  scattered  throughout 
the  world  by  commerce. 

I  have  mentioned  on  several  occasions  that  California  ex- 
tended considerably  further  westward  in  former  times,  and 
that  the  numerous  little  islands  such  as  Guadalupe,  Cerros, 
Santa  Catalina,  Santa  Eosa  and  others  are  the  visible  remains 
of  that  ancient  Pacific  land  belt.  The  fact  that  they  are  in- 
habited by  fourteen  species  and  varieties  of  reptiles  and 
amphibians*  not  known  from  the  mainland,  suggests  that  the 
islands  have  been  separated  from  the  latter  since  at  any  rate 
pre-Glacial  times. 

Now  on  the  coast  of  Chile  we  have  similar  evidence  o'f  a 
westward  extension  of  land  in  former  times.  The  tiny  deer 
known  as  the  "pudu"  occurs  in  Chile  and  Chiloe  island. 
Its  only  near  relative  lives  in  Ecuador.  The  small  mouse-like 
mammal  Acodon  brachyotis  of  Chiloe  island  and  the  Chonos 
archipelago  is  peculiar  to  these  islands,  and  so  are  many  other 
species  of  the  lower  groups  of  animals.  There  is,  in  fact, 
quite  a  considerable  assemblage  of  animals  and  plants  on 
these  islands,  indicating  a  former  westward  extension  of  the 
mainland.  Even  the  far  distant  Juan  Fernandez  island, 
which  lies  five  hundred  miles  from  the  mainland,  possesses  a 
peculiar  species  of  humming-bird  (Eustephanus  fernan- 
densis)  and  no  doubt  other  indigenous  forms  of  animal  life. 
It  is  situated  on  the  tract  of  the  old  land  belt  which  I  believe 
to  have  once  extended  from  the  west  coast  of  southern  Chile 
to  south-western  North  America,  and  from  there  eastward 
to  Europe  (Fig.  14).  In  early  Tertiary  times  already  parts  of 
this  old  land  bridge  had  disappeared,  so  that  Chile  and  south- 

*  Denburgh,   J.  van,    "  Keptiles   and  Amphibians  of    Pacific   Coast 
Islands,"  p.  4. 


ANCIENT   PACIFIC  LAND  BELT  419 

western  North  America  became  disconnected.  Yet  the  eastern 
shores  of  the  great  peninsula,  which  long  afterwards  stretched 
southward  from  the  west  coast  of  California,  joined  the  con- 
tinent of  South  America  further  north,  probably  in  Ecuador 
and  Peru  (Fig.  16).  Animals  and  plants  arriving  from  the 
north,  like  the  mastodon  above  alluded  to,  no  longer  reached 
Chile  directly,  though  still  able  to  enter  South  America  by 
this  second  route,  which  added  many  new  forms  to  the  fauna 
of  the  continent. 

This  is  all  I  have  to  say  on  the  origin  of  the  f'aunistic  and 
floristic  relationships  between  southern  South  America  and 
North  America  as  well  as  Europe.  I  have  also  referred 
above  to  a  kinship  existing  between  the  Santa  Cruz  fauna  of 
Argentina  and  the  living  fauna  of  Australia.  This  is  a  pro- 
blem of  even  greater  interest  than  that  just  discussed.  At 
any  rate,  the  testimony  in  its  favour  has  converted  many  of 
those  who  had  hitherto  looked  upon  great  changes  in  the 
disposition  of  continents  and  ocean  basins  during  the  Tertiary 
Era  as  altogether  visionary  speculations.  Some,  like  Professor 
Osborn,*  who  contends  that  the  Atlantis  hypothesis  is  highly 
improbable,  regard  the  hypothetical  reconstruction  of  a  great 
southern  continent  (Fig.  21)  uniting  South  America  with 
Australia  as  one  of  the  greatest  triumphs  of  recent  biological 
investigation.  The  theory  of  the  former  land  connection  be- 
tween southern  South  America  and  New  Zealand  or  Australia 
has  been  discussed  from  almost  every  point  of  view,  so  that  we 
possess  at  present  quite  an  extensive  literature  on  the  subject. 
A  few  years  ago  Dr.  Ortmann  summarised  the  more  important 
papers  dealing  with  this  subject,  but  many  other  essays  have 
since  been  published  throwing  further  light  on  this  fascina- 
ting problem.  The  great  majority  of  those  who  have  endea- 
voured to  account  for  the  undoubted  faunistic  or  floristic  affi- 
nities of  southern  South  America  and  the  Australian  region 
have  come  to  the  conclusion  that  it  is  due  to  the  existence  of  a 
former  antarctic  continent.  A  few,  however,  argue  that  there 
was  a  more  direct  land  connection  between  the  two  areas 
across  the  southern  Pacific,  while  some  believe  that  the  resem- 
blance in  the  fauna  and  flora  of  the  countries  referred  to  has 


Osborn,  H.  F.,  "  Age  of  Mammals,"  p.  75. 

E    E    2 


420  ORIGIN   OF   LIFE   IN   AMERICA 

arisen  partly  by  accidental  dispersal  and  partly  by  migration 
through  the  existing  continents,  when  they  were  united  by 
short  temporary  land  bridges  in  the  far  north. 

Sir  Joseph  Hooker  seems  to  have  been  the  first  to  formulate 
the  theory  of  a  former  land  connection  of  southern  lands  from 
the  occurrence  of  identical  species  of  plants  in  widely 
separated  areas.  The  first  to  mention  an  antarctic  continent 
in  this  connection  was  Professor  Ruetimeyer.  This  was 
twenty  years  later,  in  1867.  Six  years  elapsed  after  that  until 
Professor  F.  W.  Hutton  again  brought  forward  the  theory, 
expressing  his  belief  in  the  former  existence  of  an  antarctic 
land-mass  and  its  union  with  the  southern  extremities  of  the 
present  continents.  A  few  years  later  Dr.  Gill  declared  him- 
self in  favour  of  a  large  continental  mass  embracing  Africa, 
South  America  and  Australia,  his  views  being  based  on  the 
geographical  distribution  of  fishes.  The  fact  that  Dr.  Wallace 
repudiated  the  opinions  expressed  by  his  predecessors  need 
not  be  taken  too  seriously.  Since  his  great  work  on  the  geo- 
graphical distribution  of  animals  was  issued,  facts  have  been 
brought  to  light  which  are  so  overwhelmingly  in  favour  of 
some  kind  of  continuous  land  connection  between  South 
America  and  the  Australian  region  that  he  could  not  at  the 
present  day  assert,  as  he  did  then,  that  the  affinities  alluded  to 
are  mostly  due  to  accidental  dispersal  across  the  ocean,  aided 
by  the  presence  of  an  antarctic  land-mass  unattached  to  other 
continents.  Professor  Hutton  subsequently  abandoned  his 
theory  of  a  land-bridge  between  the  two  regions  by  way  of  an 
antarctic  continent  in  favour  of  a  land  connection  right  across 
the  South  Pacific  towards  the  end  of  the  Mesozoic  Era.* 

In  the  year  1891,  an  important  contribution  to  the  subject 
was  published  by  Dr.  von  Ihering.f  He  points  out  that  the 
species  of  fresh-water  Unio  from  New  Zealand  and  adjoining 
countries  have  their  nearest  allies  exclusively  in  Chile  and 
southern  Brazil,  and  that  the  fresh-water  crayfishes  (Para- 
stacidae)  show  the  same  character.  The  conclusions  he  de- 
rives from  these  and  other  facts  are  that  the  southern  portions 

*  Ortmann,  A.  E.,  "  Origin  of  Antarctic  Faunas  and  Floras,"  pp.  139 — 
i40. 

t  Ihering,  H.  von,  "  Relations  between  New  Zealand  and  South 
America,"  p.  442. 


ANTAKCTIG   PKOBLEMS  421 

of  South  America  (Archiplata)  extended  southward  in  form 
of  a  South  Pacific  antarctic  continent,  which  kept  this  area 
in  communication  with  the  Pacific  continent  during  the  whole 
of  Mesozoic  times  (Fig.  17).  From  the  latter  became  separated 
first  a  number  of  Polynesian  islands,  then  New  Zealand  and 
finally  Australia  and  New  Guinea.  Dr.  von  Ihering  deals  with 
the  same  problem  in  several  of  his  papers,  some  of  which  have 
now  been  reprinted  in  his  recent  work  entitled  "  Archhelanis 
and  Archinotis."  *  After  giving  a  brief  review  of  the  main 
features  pointing  in  favour  of  a  former  antarctic  continent 
connecting  the  Australian  region  with  South  America,  Pro- 
fessor Jacobi  f  expresses  himself  in  favour  of  the  theory.  A 
great  deal  of  additional  evidence  in  support  of  the  same  view 
was  collected  by  Dr.  H.  O.  Forbes.  J  He  cites  many  examples 
among  birds,  the  southern  pikes  (Galaxiidae),  which  occur  in 
Chile,  Patagonia,  the  Falkland  islands  and  New  Zealand,  the 
family  Cystognathidae  among  amphibians,  and  numerous 
plants f  as  illustrating  the  intimate  affinity  existing  between 
the  faunas  of  the  Australian  and  South  American  regions. 
He  also  traces  a  faunistic  relationship  between  these  regions 
and  the  Madagascar  area,  and  concludes  that  all  these 
southern  land-masses  were  once  joined  to  an  antarctic  con- 
tinent. It  is  easy  enough  to  vaguely  describe  such  a  land 
connection.  Dr.  Forbes  was  not  satisfied  to  do  this.  He 
was  the  first  to  give  a  map  clearly  indicating  how  he 
conceived  that  all  the  areas  referred  to  were  united  with  one 
another. 

Mr.  Beddard  §  briefly  discussed  the  problem  in  1895. 
While  criticising  Dr.  Forbes'  evidence  in  so  far  as  it  relates 
to  the  struthious  birds  and  penguins,  he  admits  that  there 
are  very  strong  arguments  in  favour  of  a  former  land  connec- 
tion between  Patagonia  and  the  Australian  region,  particu- 
larly when  we  take  into  consideration  the  distribution  of 
earthworms. 

As  Mr.  Hedley  aptly  remarks,  "we  may  compare  the 
shattered  biological  monuments  of  Tasmania  and  South 

*  Ihering,  H.  von,  "  Archhelenis  and  Archinotis." 

t  Jacobi,  A.,  "  Biogeographische  Gebiete,"  pp.  204 — 207. 

t  Forbes,  H.  0.,  "The  Chatham  Islands." 

§  Beddard,  F.  E.,  "Zoogeography,"  pp.  161—172. 


422  ORIGIN  OF   LIFE   IN   AMERICA 

America  to  the  broken  columns  found  by  Oriental  travellers 
in  the  ruined  and  deserted  cities  of  a  vanished  civilisation. 
And  as  an  archaeologist  may  restore  from  such  fragments  the 
fallen  temples  or  disused  aqueducts,  so  may  a  naturalist  trace 
the  missing  arches  of  life  that  once  spanned  the  gap."  Mr. 
Hedley  *  favours  the  theory  of  a  direct  land  connection  in 
Mesozoic  or  early  Tertiary  times  between  Tasmania  and 
Tierra  del  Fuego  across  the  South  Pole,  while  New  Zealand 
then  reached  sufficiently  near  this  antarctic  land  without  join- 
ing it,  to  receive  by  flight  or  drift  many  animals  and  plants. 
He  thinks  the  faint  affinity  of  Antarctica  to  Africa  would  be 
explicable  on  the  supposition  that  before  either  America  or 
Australia  had  united  with  the  former,  Africa  had  already 
broken  away  from  it. 

A  very  memorable  discussion  on  this  question  took  place 
during  the  fourteenth  annual  meeting  of  the  American 
Society  of  Naturalists  in  Philadelphia.  Reviewing  the  geo- 
logy of  the  antarctic  regions,  Professor  Heilprin  f  stated  that 
in  its  relation  to  the  other  continents  there  was  reason  to 
believe  that  Antarctica,  whether  as  a  continent  or  in  frag- 
mental  parts,  had  a  definite  connection  with  one  or  more  of  the 
land -masses  lying  to  the  north,  and  that  the  suspicion  could 
hardly  be  avoided  that  such  connection  was,  if  with  nothing 
else,  with  New  Zealand  (and  through  it  with  Australia)  and 
Patagonia.  The  facts  of  palaeontology  are  best  explained, 
according  to  Professor  Scott  J  on  the  assumption  that  the 
antarctic  land-mass  has  at  one  time  or  another  heen  connected 
with  Africa,  Australia  and  South  America,  all  of  which  once 
radiated  from  the  South  Pole,  just  as  North  America  and 
Eurasia  now  do  from  the  North  Polar  area. 

Although  Professor  Britton  §  cited  many  examples  of 
astonishingly  close  relationship  between  plants  of  Australia, 
southern  South  America  and  South  Africa,  it  is  unnecessary 
in  his  opinion  to  invoke  as  an  explanation  a  former  land  con- 
nection across  the  antarctic  region. 

Arguing  from  the  geographical  distribution  of  the  fishes, 

*  Hedley,  C.,  "  Surviving  Eefugees  in  Austral  Lands,"  pp.  3—6. 
f  Heilprin,  A.,  "  Geology  of  Antarctic  Eegions,"  pp.  306—307. 
t  Scott,  W.  B.,  "  Antarctica  Palaeontology,"  p.  310. 
§  Britton,  N.  L.,  "Origin  of  Antarctic  Flora,"  p.  311. 


ANTAECTIC   CONTINENT  423 

reptiles  and  amphibians,  Dr.  Gill*  maintained  that  the  evi- 
dence in  favour  of  a  former  antarctic  continental  area  is 
strong,  and,  in  view  of  the  affinities  of  the  species  of  the  now 
distant  regions,  the  conclusion  is  logical  that  the  time  of 
disruption  was  not  remote  in  a  geological  sense. 

So  far  as  existing  mammals  and  birds  are  concerned,  said 
Dr.  Allen,f  there  seemed  to  be  very  slight  need  for  calling  in 
the  aid  of  a  former  antarctic  continent  to  explain  their  pre- 
sent distribution.  The  distribution  of  marsupials  alone 
among  mammals  gave  a  hint  of  a  possible  former  land  connec- 
tion between  South  America  and  Australia. 

Mr.  Ancey  J  gives  a  valuable  contribution  to  the  subject 
at  issue,  founded  on  the  distribution  of  the  terrestrial 
mollusks.  The  results  of  his  enquiries  are  that  the  evident 
relationship  of  the  faunas  of  South  America  and  the  Austra- 
lian region  can  be  satisfactorily  explained  by  the  assump- 
tion of  a  former  antarctic  continent  uniting  these  land  areas. 

As  the  antarctic  problem  has  been  widely  discussed  from 
an  ornithological  standpoint,  and  since  Dr.  Forbes  and  Pro- 
fessor Milne-Edwards  have  based  their  theories  of  former 
land  connections  largely  on  the  past  and  present  range  of  the 
flightless  ratite  birds,  it  is  right  to  mention  that  Professor 
Burckhardt  §  disagrees  entirely  with  their  conclusions.  He 
does  not  dispute  the  possibility  of  former  antarctic  land  con- 
nections, especially  between  New  Zealand  and  South  America. 
But  he  does  not  consider  that  the  flightless  giant  birds  of  the 
southern  hemisphere  can  in  any  way  be  regarded  as  furnish- 
ing evidence  in  favour  of  the  theory  of  a  former  antarctic 
continent. 

From  a  zoogeographical  point  of  view,  inconspicuous 
groups  of  invertebrates,  such  as  the  earthworms,  are  of  far 
greater  value  than  birds  are.  When  the  older  writers  dis- 
cussed the  antarctic  problems  we  knew  as  yet  practically 
nothing  of  their  distribution.  Within  recent  years  several 
zoologists  have  made  a  special  study  of  this  group,  and  have 
found  that  earthworms  are  of  the  greatest  value  in  the  study 

*  Gill,  Th.,  "  Fishes,  Eeptiles  and  Amphibians  of  the  Antarctic,"  p.  315. 

t  Allen,  J.  A.,  "Birds  and  Mammals  of  the  Antarctic,"  p.  317. 

J  Ancey,  C.  F.,  "Faunes  malacologiques  australes,"  p.  27. 

§  Burckhardt,  E.,  "  Problem  des  antarktischen  Schopfungscentrum." 


424  OKIGIN   OF  LIFE   IN   AMEEICA 

of  palaeogeography.  Professor  Benham,  moreover,  has  the 
advantage  of  residing  in  New  Zealand,  so  that  his  views  on 
these  problems  are  of  peculiar  interest.  To  the  south  of  New 
Zealand,  between  the  latter  and  the  antarctic  regions,  there 
are  two  groups  of  islands,  viz.,  the  Auckland  and  Macquarie 
islands.  Now  it  is  a  specially  noteworthy  fact,  remarks  Pro- 
fessor Benham,  that  the  species  of  earthworms  from  Mac- 
quarie island,  and  those  occurring  in  the  Auckland  islands,  are 
more  nearly  allied  to  South  American  and  South  African 
species  than  to  those  of  the  mainland  of  New  Zealand.  The 
evidence  derived  from  the  distribution  of  earthworms  is,  ac- 
cording to  Professor  Benham,*  strongly  in  favour  of  the 
theory  that  New  Zealand,  South  America  and  South  Africa 
were  once  connected  with  one  another  by  land. 

A  study  of  the  fresh-water  crayfishes  yields  an  even  more 
remarkable  testimony  in  support  of  the  same  view,  at  least 
of  the  theory  that  New  Zealand  and  southern  South  America 
were  connected  by  land.  Dr.  Ortmann  points  out  that  the 
family  of  crayfishes  known  as  Parastacidae  is  confined  to 
Australia,  including  Tasmania,  New  Zealand,  southern  South 
America  and  Madagascar.  This  family  has  thus  an  extremely 
discontinuous  range  and  must  be  of  great  antiquity.  Dr. 
Ortmann  f  believes  that  the  Parastacidae  existed  in  Australia 
in  Upper  Cretaceous  times  and  thence  spread  by  a  land  con- 
nection into  Antarctica,  from  which  Parastacus  reached  Chile. 
Subsequently  Parastacus  extended  its  range  to  Argentina  and 
southern  Brazil.  Madagascar,  he  thinks,  was  not  connected 
with  the  Antarctic  Continent,  and  received  its  fresh -water 
crayfishes  by  another  route.  Besides  this  affinity  in  the  fresh- 
water crayfishes  of  the  Australian  region  and  temperate  South 
America,  there  are  other  crustaceans  showing  similar  features. 
Mr.  Geoffrey  Smith  J  tells  us  that  one  of  the  commonest 
plankton  organisms  in  the  mountain  lakes  and  tarns  of 
Tasmania  is  the  copepod  crustacean  Boeckella.  Now  this 
genus  nowhere  spreads  into  the  tropics,  yet  reappears  in 
New  Zealand  and  southern  South  America. 

*  Benham,  W.  B.,  "  Geographical  Distribution  of  Earthworms," 
pp.  329—335. 

t  Ortmann,  A.  E.,  "  Distribution  of  Decapods,"  p.  340. 
{  Smith,  Geoffrey,  "  Naturalist  in  Tasmania,"  p.  137. 


PATAGONIA   AND  NEW   ZEALAND  425 

Professor  Kolbe  contributes  a  careful  review  of  the  subject 
from  the  point  of  view  of  the  beetles  (Coleoptera).  After 
illustrating  the  intimate  relationship  that  exists  between 
southern  South  America  and  the  Australian  region,  by  means 
of  the  distribution  of  some  of  the  Carabidae,  Lucanidae,  Scara- 
baeiidae,  Buprestidae,  Elateridae  and  other  families  of  beetles, 
he  comes  to  the  conclusion  that  an  Antarctic  Continent  mu.st 
have  existed  in  early  Tertiary  times.  Professor  Kolbe*  be- 
lieves that  this  continent  was  joined  to  the  southern  parts  of 
South  America,  New  Zealand  and  Australia,  and  that  some 
genera  passed  from  the  latter  to  America,  whilst  others 
travelled  in  the  opposite  direction.  Although  the  affinities 
of  South  Africa  and  Madagascar  with  South  America  and 
Australia  are  much  less  pronounced,  Professor  Kolbe  never- 
theless urges  that  these  countries,  too,  were  to  some  extent 
connected  by  land  with  the  Antarctic  Continent. 

Dr.  Arldtf  recently  gave  us  an  excellent  summary  of  the 
most  striking  points  in  favour  of  the  theory  that  southern 
South  America  and  the  Australian  region  were  once  con- 
nected by  means  of  an  Antarctic  Continent.  The  theory  meets 
with  his  entire  approval,  but  he  concurs  with  Professor 
Hutton  and  others  in  the  belief  that  a  second  means  of  com- 
munication between  Australia  and  South  America  was  fur- 
nished by  a  mid-Pacific  land  bridge. 

Finally,  Professor  ChiltonJ  reviewed  the  problem  from  the 
point  of  view  of  New  'Zealand  and  the  neighbouring  su.b,- 
antarctic  islands  and  their  fauna  and  flora.  His  conclusions 
are  strongly  in  favour  of  a  former  land  connection  by  way  of 
the  Antarctic  Continent  between  South  America  and  New 
Zealand. 

1  have  still  to  state  my  own  opinion  on  this  subject.  That 
there  was  some  kind  of  a  direct  land  connection  between  Chile 
and  New  Zealand  and  Australia  appears  to  me  obvious.  The 
strongest  arguments  in  its  favour  are  supplied  by  the  distri- 
bution of  the  fresh-water  mussels  and  the  fresh-water  cray- 
fishes. The  genus  Diplodon,  one  of  the  Unionidae,  inhabits 

*  Kolbe,    H.,    "  Coleopteren    der    Magalhaensischen    Sammelreise," 
pp.  19 — 30  (compare  also  "Die  Siidpolarkontinenttheorie  "). 
f  Arldt,  Th.,  "  Bedeutung  der  Antarktis,"  p.  370. 
t  Chilton,  C.,  "  Biological  Eelations  of  Sub-antarctic  Islands,"  p.  806. 


426  ORIGIN  OF   LIFE   IN  AMERICA 

the  rivers  of  western  and  southern  South  America.  No  living 
Diplodon  has  ever  been  discovered  in  Central  or  North 
America,  where  other  Unionidae  are  found  in  the  greatest  pro- 
fusion. No  Diplodon  has  ever  been  discovered  fossil  either  in 
Central  or  North  America,  although  a  great  many  fossil 
Unionidae  are  known  to  science.  Hence  it  seems  certain  that 
Diplodon  has  never  lived  north  of  its  present  habitat.  Yet 
in  New  Zealand,  in  Tasmania  and  Australia  this  genus  re- 
appears. Further  north  in  Asia  it  has  never  been  met  with. 
Some  zoologists  are  of  opinion  that  affinities  such  as  the  one 
alluded  to  can  be  interpreted  by  the  supposition  of  a  former 
sub-universal  distribution  and  a  subsequent  extinction  in  all 
but  the  present  habitats.  We  do  not  possess  a  shadow  of  any 
evidence  for  such  a  belief,  in  so  far  as  the  range  of  the  fresh- 
water mussel  Diplodon  is  concerned. 

Let  us  take  the  second  case,  that  of  the  fresh-water  cray- 
fishes. Crayfishes  are  abundant  in  the  streams  of  North 
America  and  Asia,  but  they  all  belong  to  the  family  Potamo- 
biidae,  while  southern  South  America  is  inhabited  by  quite  a 
different  family,  the  Parastacidae.  Crayfishes  of  the  latter 
family  are  again  met  with  on  the  other  side  of  the  Pacific,  but 
only  in  the  extreme  south,  in  New  Zealand,  Tasmania  and  Aus- 
tralia. Neither  of  these  instances  can  be  due  to  convergence, 
nor  to  a  passage  from  one  continent  to  the  other  by  way  of 
the  northern  continents.  A  direct  land  bridge  becomes  abso- 
lutely essential,  yet  this  need  not  necessarily  have  lain  in  the 
direction  of  the  antarctic  regions.  Its  position  might  have  been 
further  north,  as  suggested  by  Professor  Hutton,*  although 
the  latter  has  more  recently  revised  his  theories,  in  so  far 
as  he  now  advocates  two  south  Pacific  land  bridges,  instead 
of  a  single  one  as  previously  maintained.  In  1905  he 
announced  that,  having  reconsidered  his  former  conclusions, 
he  believed  that  an  Antarctic  Continent  existed  in  Jurassic 
times  which  connected  South  America  with  New  Zealand  and 
South  Africa.  He  thinks  that  this  continent  sank  in  the  Cre- 
taceous Period,  Antarctica  never  having  since  been  connected 
with  northern  lands.  Subsequently,  either  during  Cretaceous 
or  early  Tertiary  times,  a  Pacific  Continent  must  have  united 

*  Hutton,  F.  W.,  "  Ancient  Antarctica,"  p.  245. 


PACIFIC   CONTINENT  427 

New  Zealand  with  Chile,  which,  as  he  maintains,  ceased  to 
exist  at  the  close  of  the  Eocene  Period. 

Certain  geological  features  no  doubt  point  to  a  former  west- 
ward extension  of  Chile.     Dr.  Burckhardt  *  showed  that  in 
western  Chile  there  are  enormously  thick  deposits  of  porphy- 
ritic  conglomerates  which  become  more  attenuated  and  com- 
posed  of   lighter   sandy  material   as   we   proceed   eastward. 
Hence  he  argues  that  these  deposits  were  laid  down  on  an 
ancient  shore-line  of  a  vast  western  land-mass  of  which  the 
existing  coast  cordillera  of  Chile  is  the  last  remnant.     He 
advocates,  in  fact,  nothing  short  of  what  we  might  call  a 
Pacific  Continent  which  lay  mainly  to  the  westward  of  Chile. 
That   land   formerly   extended  in  that  direction  I  have  en- 
deavoured to  demonstrate  from  purely  faunistic  evidence,  but 
I  believe  that  it  was  part  of  a  great  circum-Pacific  belt  of 
land  which  stretched  mainly  northward,  communicating  from 
time  to  time  with  Central  America  and  the  Antilles,  and  also 
with  Mexico  and  western  California,  and  then  eventually  bend- 
ing across  to  eastern  Asia  in  a  great  loop  and  thus  joining 
New   Guinea,    Australia  and   New  Zealand.      That   Central 
America  and  western  North  America  must  have  been  thus 
connected  by  land  with  the  Australian  region  has  been  urged 
above   on   several   occasions   when  dealing  with   the   North 
American  fauna.    It  might  be  argued  that  if  such  a  northern 
land  connection  once  existed,  uniting  Chile  with  the  Austra- 
lian region,  there  would  no  longer  be  any  necessity  for  postu- 
lating an  antarctic  land  bridge.   Professor  Dahl  has  recently 
taken  up  this  attitude,*  illustrating  his  adverse  criticism  against 
the  antarctic  theory  by  means  of  the  distribution  of  spiders. 
He  does  not  adopt,  of  course,  my  view  of  a  northern  semi- 
circular land  belt  because  this  theory  has  never  before  been 
published  and  is  entirely  my  own.    His  contention  is  that  the 
continents  and  oceans  have  remained  within  the  lifetime  of 
the  present  fauna  what  they  are  now,  that  is  to  say,  within 
the  more  recent  geological  periods,  except  that  the  great  land- 
masses  were  joined  in, the  north.  A  powerful  centre  of  dispersal 
existed  in  the  arctic  regions,  according  to  Professor  Dahl.f 

*  Burckhardt,  0.,  "  Traces  d'un  ancien  continent,"  pp.  186 — 190. 
t  Dahl,  F.,  "  Die  Verbreitung  der  Spinnen." 


428  ORIGIN   OF  LIFE   IN   AMERICA 

and  from  it  streamed  forth  practically  all  life,  which  eventually 
reached  the  most  southern  tips  of  the  continents.  We  thus  not 
only  find  there  the  oldest  forms  congregated  together,  accord- 
ing to  Professor  Dahl,  but  these  would  naturally  resemble  one 
another  in  all  the  southern  parts  of  the  continents.  It  is 
a  simple  theory,  and  at  first  sight,  as  I  mentioned  before, 
when  discussing  the  similar  views  of  Dr.  Haacke,  it  seems 
to  put  before  us  the  solution  of  all  the  problems  of  dispersal 
in  a  satisfactory  manner.  No  one,  however,  who  has  taken 
the  trouble  to  read  this  book,  can  for  a  moment,  I  venture  to 
think,  perceive  any  justification  for  holding  such  a  belief  as 
that  of  Professor  Dahl's.  There  may  possibly  have  been  such  a 
centre  of  dispersal  as  that  suggested,  but  it  was  long  before 
any  geological  records  existed.  Any  forms  of  animal  life  that 
we  are  acquainted  with  show  clearly  and  unmistakably  that 
there  have  been  scores  of  great  centres  of  dispersal  in  the 
world,  and  that  from  them  streamed  forth  new  forms  in  every 
available  direction.  Northern  animals  advanced  southward 
and  southern  forms  northward,  aided,  no  doubt,  by  the  ever- 
changing  conditions  of  climate  and  the  gradual  evolution  of 
oceans  and  continents. 

To  return  to  the  question  at  issue,  let  us  examine  what  light 
the  marine  fauna  throws  on  the  problem.  The  geographical 
distribution  of  the  elephant  seal  (Macrorhinus  leoninus), 
which  occurs  on  the  shores  of  southern  South  America,  of 
the  antarctic  lands,  of  New  Zealand  and  Tasmania,  will  not 
contribute  much  to  its  solution,  but  some  of  the  inverte- 
brates are  of  more  importance.  The  Eocene  beds  of  Pata- 
gonia,  as  well  as  those  of  New  Zealand,  contain  several  species 
of  marine  mollusks  common  to  both,  such  as  Cucullaea  alta, 
Scalaria  rugulosa  and  Turritella  ambulacrum.  Other  Pata- 
gonian  species,  for  example,  Brachydontes  magellanica,  Tur- 
ritella patagonica  and  Crepidula  gregaria  only  appear  in  New 
Zealand  in  later  deposits.  Besides  these  species  the  older 
Tertiaries  of  the  two  countries  have  a  large  number  of  genera 
common  to  both.  Dr.  von  Ihering  *  thus  concludes  with  con- 
siderable justification  that  the  geographical  conditions  during 
early  Tertiary  times  must  have  been  favourable  for  a  dis- 

*  Ihering,  H.  von,  "Mollusques  Fossiles  de  L' Argentine,"  p.  499. 


MAKINE   FAUNA  OF   PATAGONIA  429 

persal  of  marine  mollusks  between  Patagonia  and  New  Zea- 
land. It  is  interesting  to  note  that,  whereas  this  faunistic 
interchange  took  place  between  Patagonia  and  New  Zealand, 
the  early  Tertiary  Chilean  fauna  exhibits  scarcely  any  traces 
of  relationship  with  that  of  New  Zealand. 

If  the  ancient  land  connection  between  southern  South 
America  and  New  Zealand  had  been  a  westward  extension  of 
the  coast  of  Chile,  we  should  expect  a  greater  resemblance 
between  the  old  Tertiary  fauna  of  the  latter  country  and  New 
Zealand  than  between  Patagonia  and  New  Zealand.  The  evi- 
dence derived  from  the  Eocene  mollusks  of  Patagonia  and 
New  Zealand  is,  therefore,  in  favour  of  a  southern  land  con- 
nection by  way  of  the  antarctic  regions.  I  cannot  believe  that 
an  Antarctic  Continent,  in  the  sense  of  Forbes  or  0 shorn, 
could  have  existed  at  that  time.  If  the  affinity  of  the  marine 
faunas  of  Patagonia  and  New  Zealand  was  due  to  a  con- 
tinuous shore -line  between  the  two  countries,  Chile  must 
have  extended  southward  beyond  Tierra  del  Fuego  and  then 
have  curved  across  to  New  Zealand  in  a  great  loop.  The  Pata- 
gonian  fauna  spread  to  New  Zealand  on  the  south  side  of  the 
latter.  Hence  the  South  Polar  region  must  have  been  largely 
covered  by  sea  at  that  time.  At  any  rate,  I  believe  in  the 
former  existence  of  two  land  connections  between  Chile  and1 
New  Zealand,  one  by  way  of  North  America  and  eastern  Asia, 
the  other  directly  across  the  South  Polar  area. 

This  leads  us  'to  the  third  problem  connected  with  that 
extraordinarily  interesting  region  of  southern  South  America, 
namely,  its  direct  affinities  with  the  anntarctic  regions,  and  in- 
cidentally with  South  Africa  and  Madagascar.  The  southern 
tip  of  Tierra  del  Fuego  bends  eastward.  At  its  eastern  ex- 
tremity lies  Staten  island,  and  beyond  it  the  great  Burdwood 
Bank.  North  of  the  latter,  at  no  great  distance,  are  situated 
the  Falkland  islands.  Nowhere  is  there  a  greater  depth  of 
water  than  a  hundred  fathoms  between  the  latter  arid  the 
mainland.  Consequently  all  this  presumably  was  once  part  of 
South  America. 

The  Falkland  islands  cover  an  area  of  about  half  the  size 
of  Ireland,  lying  three  hundred  and  fifty  miles  east  of  Pata- 
gonia. The  country  consists  of  undulating  moorland,  with  an 
abundance  of  peaty  soil  yielding  an  ample  supply  of  wiry 


430  ORIGIN   OF  LIFE   IN   AMERICA 

grass  with  a  growth  of  bushes  here  and  there.  As  Darwin 
pointed  out  long  ago,  almost  the  whole  of  the  islands  are  com- 
posed of  sedimentary  rocks,  such  as  clay-slate  and  sandstone, 
while  the  hills  are  formed  of  white  granular  quartz.  Darwin* 
considered  the  sandstone  of  Silurian  age,  whereas  Mr. 
Newton,f  who  has  recently  examined  the  fossils  brought  back 
by  Dr.  Bruce,  shows  that  they  belong  to  the  Devonian  Period, 
many  of  them  being  identical  with  South  African  species  of 
similar  age. 

No  clue,  however,  can  be  obtained  from  the  geological  fea- 
tures as  to  the  age  of  the  islands,  or,  as  we  might  say,  the 
time  when  the  latter  became  separated  from  the  mainland. 
We  are  thus  obliged  to  seek  for  information  from  the  exist- 
ing animals  and  plants.  Mr.  Vallentin's  J  account  of  the 
fauna  and  flora  only  deals  with  the  general  features,  such  as 
a  casual  visitor  might  notice.  He  informs  us  that  no  indi- 
genous mammals  occur  on  the  Falkland  islands,  as  the  peculiar 
wolf  (Canis  antarcticus)  which  once  lived  there  is  now  ex- 
tinct. It  is  still  customary  to  connect  this  Falkland  island  wolf 
with  some  of  the  mainland  species,  although  Mr.  Lydekker  § 
pointed  out  long  ago  that  it  differs  markedly  from  all  the  dog- 
and  wolf-like  creatures  (Canidae)  of  South  America,  being 
closely  allied  to  the  North  American  coyote  (Canis  latrans). 
Dr.  von  Ihering  ||  places  it,  along  with  the  coyotes,  into  the 
sub-genus  Lyciscus,  whereas  the  remaining  South  American 
species  of  the  family  belong  to  Chrysocyon,  Carcinocyon  and 
other  genera.  Neither  of  these  writers  dwell  upon  the  causes 
of  this  altogether  extraordinary  range.  Are  we  to  regard  this 
as  an  instance  of  convergence  ?  I  scarcely  think  that  any 
mammalogist  will  maintain  such  a  view.  And  yet  how  are  we 
to  account  for  the  fact  of  the  existence  in  these  remote  islands 
of  a  mammal  whose  nearest  relatives  are  all  confined  to  North 
America  ?  It  is  an  extremely  interesting  problem.  I  have 
alluded  to  the  noteworthy  fact  more  than  once  that  Chile,  and 
even  Tierra  del  Fuego  and  Argentina,  exhibit  a  very  surprising 

*  Darwin,  0.,  "Journal  of  Kesearches,"  p.  142. 

t  Newton,  E.  T.,  "  Fossils  from  Falkland  Islands,"  p.  251. 

1  Vallentin,  E.,  "  Voyage  to  the  Falklands,"  p.  352. 

§  Lydekker.  E.,  "  Geographical  History  of  Mammals,"  p.  140. 

||  Ihering,  H.  von,  "  Verbreitung  d.  Siidamerik.  Eaubtiere,"  p.  153. 


THE   FALKLAND   ISLANDS.  431 

faunistic  relationship  with  western  North  America,  but  this 
affinity  seems  to  be  confined  to  very  ancient  groups  of  verte- 
brates and  invertebrates.  I  ventured  to  allude  to  the  North 
American  porcupines  as  being  possibly  the  descendants  of 
Steiromys,  which  I  suggested  had  utilised  the  early  Tertiary 
land  connection  from  Chile  to  Mexico  or  California.  Stei- 
romys, however,  is  long  since  extinct.  If  we  suppose  the 
coyotes  to  have  taken  advantage  of  that  land  connection  in 
early  Tertiary  times,  we  might  assume  a  member  of  that  early 
fauna  to  have  succeeded  in  surviving  in  these  lonely  islands 
until  recent  times.  But  the  difficulty  in  accepting  such  an 
hypothesis  is  that  it  would  give  the  coyotes  a  much  longer 
ancestry  than  any  palaeontologist  would  care  to  admit.  Never- 
theless it  is  the  only  theory  I  can  suggest.  Another  question 
that  occurs  to  me  is — If  the  wolf  was  the  only  mammal  in- 
habiting the  Falkland  islands,  what  did  it  live  on  ?  Wolves  are 
carnivorous,  as  everyone  knows,  usually  feeding  on  smaller 
mammals.  Yet  Darwin  states  that  it  is  the  only  quadruped 
native  to  the  islands  ;  he  adds,  however,  in  a  footnote,  "  I  have 
reason  to  suspect  there  is  also  a  field  mouse."  This  is  probably 
a  species  of  Keithrodon  or  some  allied  genus.  Still  this 
mouse -like  creature  could  scarcely  have  constituted  the  sole 
food  of  such  a  large  animal  as  the  wolf.  In  all  likelihood, 
some  larger  rodent  existed  on  the  islands  and  may  have 
become  extinct  before  the  advent  of  man.  The  wolf  soon  after 
this  event  shared  the  same  fate. 

An  examination  of  the  earthworm  fauna,  which  is  probably 
of  very  great  antiquity,  reveals  the  fact  that  there  are  living 
on  the  Falkland  islands  two  species  of  the  genus  Noteo- 
drilus  (N.  bovei  and  N.  falclandicus)  which  otherwise  is  con- 
fined to  South  and  Central  America,  New  Zealand,  Australia, 
Cape  of  Good  Hope,  Madagascar  and  several  of  the  antarctic 
islands.  A  second  genus,  viz.,  Chilota,  which  is  represented  on 
the  Falkland  islands  by  Chilota  daleti,  inhabits  only  southern 
South  America  and  the  Cape  of  Good  Hope,  with  the  exception 
of  a  single  species  living  on  the  Cape  Verd  islands.  The  third 
genus,  Yagansia,  has  not  yet  been  found  on  the  Falkland 
islands.  It  is  almost  peculiar  to  Chile  and  Argentina.  Only 
one  species  of  Yagansia  has  been  met  with  in  South  Africa.* 
*  Michaelsen,  W.,  "  Verbreitung  d.  Oligochaeten,"  p.  74. 


432  OEIGIN   OF   LIFE   IN   AMEBICA 

Thus  there  appears  to  he  a  distinct  faunistic  affinity  between 
southern  South  America  as  a  whole,  including  the  Falkland 
islands,  and  New  Zealand,  as  well  as  South  Africa  and  Mada- 
gascar. I  have  already  alluded  to  Professor  Bouvier's  *  re- 
markable discovery  of  the  Peripatus  of  Chile  being  more 
closely  allied  to  that  of  South  Africa  'than  to  those  of  the  rest 
of  South  America,  so  that  he  now  places  the  South  African 
and  Chilean  species  into  the  genus  Opisthopatus,  while  all 
the  rest  remain  in  the  old  genus  Peripatus.  I  have  likewise 
drawn  attention  to  the  fact  that  the  family  of  fresh-water  cray- 
fishes Parastacidae  occurs  only  in  southern  South  America,:  the 
Australian  region  and  Madagascar.  Professor  Kolbe  f  argued 
long  ago  that  the  manifold  faunistic'  affinities  of  South 
America  and  Madagascar  were  largely  due  to  an  immigration 
into  the  latter  of  American  forms  from  the  south  by  means 
of  antarctic  land  connections.  Lastly,  there  are  relationships 
even  among  the  marine  forms  of  Patagonia  and  South  Africa 
which  seem  to  demand  the  existence  of  a  former  direct  land 
connection  between  these  areas,  although  Dr.  Ashworth  J 
would  join  'the  latter  to  an  Antarctic  Continent.  When  ,the 
faunas  of  Madagascar  and  South  Africa  become  better  known, 
it  will  be  possible  to  follow  these  clues  with  greater  success. 
That  these  affinities  are  altogether  of  the  nature  of  con- 
vergences, as  some  authorities  would  have  us  believe,  is,  I 
think,  inadmissible.  If  they  are  due  to  the  existence  of 
former  antarctic  land  connections,  we  may  be  sure  that  they 
are  of  very  great  antiquity,  possibly  far  beyond  the  limits  of 
the  Tertiary  Era. 

Stimulated  largely  by  these  zoogeographical  problems,  the 
antarctic  regions  have  within  recent  years  received  a  greater 
share  of  public  attention  than  hitherto.  Thus  expeditions, 
have  been  fitted  out  from  Belgium,  France,  Germany,  Eng- 
land and  Scotland  in  order  to  endeavour  to  throw  light  on 
some  of  these  mysteries.  Interesting  results  in  connection 
with  the  theories  of  a  former  land  connection  between 
South  America  and  Madagascar  were  obtained,  particularly 
by  the  Scottish  Antarctic  Expedition.  Eeturning  northward 

*  Bouvier,  E.  L.,  "  Monographic  des  Onychophores,"  pp.  64 — 65. 

t  Kolbe,  H.  J.,  "  Zoogeographische  Elemente  in  Madagascar,"  p.  173. 

%  Ashworth,  J.  H.,  "  Arenicolidae  of  South  Africa,"  p.  23, 


ANTARCTIC  EXPEDITIONS  433 

from  the  South  Polar  regions,  Dr.  Bruce  took  a  series  of 
soundings  proving  that  the  South  Atlantic  rise  extended 
a  thousand  miles  further  south  than  was  previously  known. 
Now  Dr.  Bruce  believes  that  this  comparatively  shallow 
water  area  extends  westward  to  the  Sandwich  group  (not 
to  be  confounded  with  the  Sandwich  islands  in  the  Pacific 
Ocean),  and  eastward  to  Bouyet  island.  By  demonstrating 
the  presence  of  a  long  ridge  of  about  three  hundred  miles 
in  breadth  between  Madagascar  and  Bouvet  island  to  the 
Sandwich  group,  with  a  forked  connection  towards  the  South 
Orkneys  a  ad  the  antarctic  regions  on  the  one  hand,  and  the 
Falkland  islands  and  Tierra  del  Fuego  on  the  other,  Dr. 
Bruce  *  has  made  a  valuable  addition  to  our  knowledge  of  the 
zoogeographical  affinities  referred  to. 

Professor  Carpenter  ,f  who  described  the  Collembola  brought 
back  from  the  South  Orkney  islands  by  the  Scottish  antarctic 
Expedition,  concludes  that  these  minute  insects  support  the 
view  of  the  former  existence  of  extensive  land  tracts  south  of 
the  American  continent.  It  may  be  mentioned  incidentally 
that  sedimentary  rocks  have  now  been  discovered  not  only  in 
the  South  Orkney  islands  by  Dr.  Pirie,  but  also  in  the  island 
of  South  Georgia. 

A  very  important  contribution  to  the  subject  of  the 
antarctic  problem  is  that  by  Dr.  Enderlein.  He  deals  with 
the  geographical  distribution  in  the  South  Polar  regions 
of  insects  as  a  whole.  Chile,  Tierra  del  Fuego,  the  Falk- 
land islands  and  South  Georgia  all  belong,  according  to  him, 
to  Dr.  von  Ihering's  "  Archiplata  "  region,  while  the  Auck- 
land isles,  Campbell  islands  and  the  Macquarie  islands  are 
grouped  as  part  of  New  Zealand.  The  former  has  a  large  num- 
ber of  endemic  genera  of  insects.  Dr.  Enderlein  regards  the 
family  Thynnidae  as  one  of  the  most  valuable  supports  in 
favour  of  a  former  land  connection  between  Archiplata  and  the 
whole  Australian  region,  all  the  females  of  this  family  of 
Hymenoptera  being  wingless.  'These  insects  are  confined  to 
the  Australian  region  and  southern  South  America.  Numbers 
of  similar  instances  are  cited.  After  quoting  all  the  recorded 

*  Bruce,  W.  S.,  "Survey  of  South  Atlantic,"  p.  10. 
f  Carpenter,  G.  H.,  "  Collembola  from  South  Orkneys,"  p  479. 
L.A.  F   F 


434  OBIGIN  OF  LIFE  IN   AMERICA 

insects  from  the  antarctic  regions,  Dr.  Enderlein  comes  to 
the  conclusion  that  the  existing  features  of  distribution  are 
best  explained  by  means  of  Dr.  Simroth's  pendulation  theory. 
That  theory  is  founded  on  the  supposed  pendulation  or  shifting 
of  the  poles  in  the  course  of  time.  As  the  South  Pole  gradu- 
ally travelled  northward,  the  present  antarctic  regions  would 
have  slowly  moved  into  more  favourable  climatic  regions,  and 
have  thus  become  habitable  for  such  temperate  animals  and 
plants  as  were  able  to  reach  them.  When  the  Pole  once  more 
moved  back  towards  its  present  position,  the  antarctic  fauna 
and  flora  would  again  have  endeavoured  to  regain  suitable 
climatic  regions  by  any  other  land  connections  then  available. 
In  this  manner  it  is  perfectly  conceivable  how,  by  a  combina- 
tion of  serviceable  land  connections  and  a  shifting  Pole,  the 
present  geographical  distribution  of  the  animals  and  plants 
alluded  to  could  have  been  brought  about.  We  need  not 
imagine  the  former  existence  of  a  huge  continent  from  which 
long  peninsulae  projected,  simultaneously  joining  all  the 
southern  continents  with  one  another.  More  slender  land 
bridges  uniting  one  continent  after  another  during  succes- 
sive geological  ages  with  an  antarctic  land-mass  would  be 
sufficient.  Dr.  Enderlein  supposes  that  probably  towards  the 
end  of  Cretaceous  or  in  Eocene  times  the  antarctic  "  Heard- 
Marion,"  area  was  connected  by  land  with  Madagascar  and 
indirectly  with  South  Africa.  Tierra  del  Fuego  extended 
beyond  the  Falkland  islands,  South  Georgia,  South  Orkneys 
and  Shetlands  to  Antarctica  about  the  same  time,  and  also, 
perhaps  during  the  Oligocene  and  Miocene  Periods.  Australia 
was  joined  to  the  same  area  in  Oligocene  or  Miocene  times. 
Dr.  Enderlein,*  on  the  other  hand,  believes  New  Zealand  to 
have  been  completely  isolated  from  all  other  regions  since  the 
Eocene  Period. 

The  theory  appears  simple  and  plausible,  and  if  it  should  be 
proved  that  the  Poles  shift  their  position  to  the  extent  assumed 
by  Professor  Simroth,  it  would  explain  the  causes  of  some  of 
the  great  movements  of  animal  life  in  a  satisfactory  manner. 
Nevertheless,  we  cannot,  as  Dr.  Enderlein  acknowledges,  dis- 

*  Enderlein,  Gunther,  "  Biologische  Bedeutung  der  Antarktis," 
pp.  333—350. 


PENDULATION   THEORY  435 

pense  with,  land  connections,  and  he  rejects  the  theories  of 
accidental  dispersal  as  quite  inapplicable  to  the  solution  of  the 
antarctic  biological  problems.  For  my  own  part,  I  think  that 
changes  of  land  and  water,  combined  with  warm  currents  in 
the  Polar  regions,  would  likewise  explain  the  same  phenomena 
in  a  satisfactory  manner,  and  I  prefer  to  adopt  the  latter  view 
until  we  possess  more  definite  information  as  to  evidence  on 
which  the  pendulation  theory  is  founded. 

I  have  endeavoured  in  this  work  to  show  how  the  gradual 
evolution  of  our  continents  and  the  former  changes  of  land 
and  water  can  be  demonstrated  by  a  study  of  the  geographical 
distribution  of  living  animals  and  plants.  Whenever  possible 
I  have  taken  advantage  of  our  palaeontological  and  geological 
knowledge  in  furtherance  of  this  object,  and  I  venture  to 
think  that  I  have  succeeded  in  unravelling  some  intricate 
problems  of  the  palaeogeography  of  America.  Indirectly  I 
have  thus  been  able  to  indicate  the  manner  in  which  North 
and  South  America  became  populated,  and  the  extent  to 
which  these  continents  took  part  in  supplying  animals  and 
plants  to  other  regions  of  the  world. 


F  F 


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(Part  I.). 

WOODWARD,  A.  S.  "  On  some  extinct  Reptiles  from  Patagonia  of 
the  genera  Miolania,  Dinilysia  and  Genyodectes."  Proc.  Zool.  Soc. 
London,  pp.  169—184.  1901  (Part  I.). 

WOODWARD,  S.  P.  "A  Manual  of  the  Mollusca"  (3rd  ed.). 
London,  1875,  with  appendix  by  'Ralph  Tate. 

WORTMAN,  J.  L.  "  Psittacotherium,  a  member  of  a  new  and  primi- 
tive sub-order  of  Edentata."  Bull.  Amer.  Mus.  Nat.  Hist.,  Vol.  VIII., 
pp.  259—262.  1896. 

WRIGHT,  G.  F.  and  W.  Upham.  "  Greenland  Icefields,  and  Life 
in  the  North  Atlantic."  London,  1896. 

ZITTEL,  K.  A.  VON.  "Handbuch  der  Palaeontologie."  5  vols. 
Munchen,  1876—1893. 


INDEX 


A 


Acanthonyx  petiverii,  333 

Accidental  distribution,  of  butterflies, 
116,  117  ;  of  snakes,  130  ;  as  ap- 
plied to  Bermuda,  192,  194  ;  of 
freshwater  fishes,  232  ;  in  Antilles, 
265  ;  of  animals  and  plants  in  Gala- 
pagos islands,  300,  301,  306,  309 

Achatellina,  308 

Achatina  achatina,  380 

Achatinidae,  380,  390 

Acodon  brachyotis,  418 

Actoniscus  ellipticus,  190 

ADAMS,  life  in  Alaska  during 
Glacial  Epoch,  34,  35  ;  southward 
retreat  of  fauna  and  flora  during 
Ice  Age,  35,  37,  38  ;  centres  of  dis- 
persal in  south-east  and  south-west, 
174  ;  "  biotic  preserves,"  174 

Adelopoma,  257,  273  ;  stolli,  257  ; 
martensi,  257 

AegialUis  sanctae-helenae,  387 

Aeglea  laevis,  405 

Aegleidae,  405 

Aesirelata  phaeopygia,  302 

Agapeta,  350 

Ag arista,  214 

AGASSIZ,  A.,  subsidence  of  Bahamas, 
185  ;  origin  of  Galapagos  islands,  296  ; 
ocean  floor  off  Panama,  332,  333 ; 
relict  fauna  in  Lake  Titicaca,  361 

AGASSIZ,  L.,  faunistic  isolation  of  New 

England,  56,  57 
Aglossa,  377 

Agonostomus,  290  ;   monticola,  290 
Agraulis,  179 

Agrotis  exclamatianis ,  214 
Alaska,  description  of,  74,  75  ;  Glacial 
Epoch  in,  76,  81  ;     "  black  muck  " 
deposits,  79  ;    fauna  in  Pleistocene, 


78—81  ;  mammalian  fauna,  91,  92  ; 
flora,  92,  93 

Alberta,  game  preserves  in,   119 

Aloes,  americanus,  32;  bedfordiae,  32; 
machlis,  32  ;  gigas,  92 

ALCOCK,  dispersal  of  Coeciliidae,  251 

ALLEN,  G.  M.,  mammals  of  West 
Indies,  282 

ALLEN,  J.  A.,  species  of  reindeer,  5  ; 
species  of  musk-ox,  7,  8  ;•  polar  origin, 
of  life,  23  ;  Glacial  Epoch,  views 
on,  34  ;  Bering  Strait  land-bridge, 
85  ;  American  mammalian  types  in 
Asia,  85  ;  opossums,  182  ;  specific 
distinctions  of  Solenodon,  282  ; 
mammalia  of  Galapagos,  298,  299  ; 
affinities  of  antarctic  lands,  423 

Alligator,  179,  180,  319  ;  missusip- 
piensis,  179  ;  sinensis,  180 

Allorchestes  dentatus,  361 

Alsophis,  288 

ALSTON,  mammals  of  Central  America, 
248 

Alytes,  204 

Amalia,  wide  distribution  of,  213,  214, 
389  ;  hewstoni,  213  ;  gagates,  213  ; 
pomonbyi,  214  ;  pectinata,  214 

Amathusidae,  369 

Amazon  River,  363 

AmUyopsidae,   164—166 

Amblyopsis  spelaeus,  165 

Amblyrhiza,  267  ;  inundata,  285 

Amblyrhynchus ,  302  ;    cristatus,  304 

Amblystoma,  136,  137  ;  tigrinum,  136, 
137;  persimile,  137;  jeffersonianum, 
137 

AMEQHINO,  tree-porcupine  in  Santa 
Cruz  beds,  71  ;  deer  in  upper  Mio- 
cene of  Argentina,  109  ;  affinities  of 
Phlaocyon,  151,  152;  southern  origin 
of  edentates,  244  ;  South  America 


472 


INDEX 


as  source  of  Tertiary  mammalia, 
244,  397  ;  ancestral  types  of  coypu, 
283;  Cuban  cave  man,  285;  geologi- 
cal history  of  South  America,  341  ; 
origin  of  American  bears,  351;  origin 
of  Viscaciidae,  353,  354  ;  lemuroid 
remains  in  Patagonia,  364,  365  ; 
South  Atlantic  land-bridge,  365, 
370,  371  ;  sloth  remains,  365  ; 
opossum  remains,  367  ;  freshwater 
deposits  of  Buenos  Aires,  397  ;  dis- 
coveries of  Tertiary  fauna,  397,  398 ; 
ancestors  of  huanaco,  406 

Ameiurus  cantonensis,  89 

Ameiva,  288 

American  animals    in  Asia,  85,  86 

Amia  calva,  163 

Amiidae,  163 

Amphibians,  in  Hudson  Bay  region, 
37  ;  relationships  of  east  American 
and  Asiatic,  135 — 137;  relationship 
of  American  and  south  European, 
137,  138,  172  ;  rarity  of,  in  south- 
western States,  204 

Amphibulima,  271 

Amphicyclotus,  257,  268 

Amphipyra  pyramided,  214 

Amphisbaena,  288,  375  ;   ridleyi,  385 

Amphisbaenidae,  173,  202,  288,  375 

Amphiuma  means,  172 

Ampullaria,  origin  in  Brazil,  362  ; 
absent  from  Chile,  405 

Anadenulus,  212 

Anadenus,  213 

Anarta,  melanopa,  22,  36  ;  leucocycla, 
22  ;  lapponica,  22 

ANCEY,  southern  distribution  of  mol- 
lusks  explained  by  Antarctic  con- 
tinent, 423 

Anchitherium,  148 

ANDERSEN,  geographical  distribution 
of  bats,  299 

Andes,  flora  related  to  that  of  Rocky 
Mountains,  104 

ANDREAE,  Atlantic  land-bridge  in 
Miocene  times,  272  ;  distribution  of 
Adelopoma,  257 

ANDREWS,  fossils  of  the  Fayum  in 
Africa,  358,  373  ;  land  connection 
between  South  America  and  north 
Africa,  278,  373 


Androdon,  350 

Anemone,  origin  and  distribution  of, 

114 
Anguidae,  202,  281,  347,  348 

Anguis,  281 

Anniella,  202 

Anniellidae,  202 

Anodons  on  Pacific  slope  of  North 
America,  162 

Anodonta,  marginata,  52  ;  kennicotti, 
52  ;  pepiniana,  52 

Anops,  376;  kingi,  376;  africanus,  376 

Anosia  archippus,  117 

Antarctic  continent,  419 — i26 

Ants,  in  Bermuda,  189  ;  in  south-wes- 
tern States,  215—217 

Antilles,  characteristics  of  fauna,  261; 
geology  and  form  of  islands,  262, 
264,  286  ;  past  geography  as  shown 
by  mollusks,  265 — 271  ;  affinities  of 
fauna,  265—278 ;  affinities  explained 
by  land-bridge,  274  ;  mammalian 
fauna,  282 — 285  ;  birds  of,  289  ; 
summary  of  geological  development, 
292—294  ;  Bahamas,  288,  289  ; 
Cuba,  261,  262,  285,  290,  291  ; 
Jamaica,  284,  288  ;  Portorico,  288 

"Antillean  continent,"  237,  241 

Antilocapra  americana,  112 

Antilocafridae,  112,  113 

Antlers  of  deer,  development  of,  108, 
111,  112 

Aphallarion,  212 

Aplexa  hypnorum,   72 

Aplodontla,  228 

Apocrypha,  413 

"  Apollo  "  butterflies,  90,  91 

APPELL^F,  opposition  to  subsidence 
theory  of  Faroe  Bank,  17,  18 

Archaean  land-mass  in  West  Indian 
region,  177 

Arctia  quenselii,  36  ;  caja,  214 

Arctoryctes,  246,  404 

Arctotherium  vetustus,  351 

Arenicola  marina,  16 

Argentina,  395,  396  ;  geological  his- 
tory of,  397  ;  former  climate,  401  ; 
connections  with  North  America, 
402,  403  ;  with  Australia,  403,  404 

Argynnis,  235,  413  ;  chariclea,  22  ; 
polaris,  22 


INDEX 


473 


ARLDT,  connection  between  Asia  and 
North  America,  97  ;  Archaean  rocks 
on  oceanic  islands,  277  ;  reptiles 
and  mollusks  in  Galapagos  islands, 
314  ;  land-connection  to  Galapagos 
islands,  316  ;  parallelism  of  Pacific 
islands,  327  ;  former  geographical 
conditions  of  South  America,  343, 
344  ;  on  Atlantic  land-bridge,  383  ; 
connection  between  South  America 
and  Australian  region,  425 

Armadillo  in  Bridger  deposits,  244  ; 
in  Santa  Cruz  beds,  399,  401  ;  in 
North  America,  401 

Armadillo  (Isopod),  309 

ARNOLD,  climate  of  Pleistocene 
Period,  94—96 

ArthrocomiLS,  413 

Armcola  (see  Microtus  and  Pitymys). 

Ascaphus,  204 

Ascension  island,  396 

Ashmunella,  206 

ASIIWORTH,  distribution  of  marine 
shore  forms,  16  ;  marine  worms  of 
Patagonia  and  south  Africa,  432 

Asiatic  types  in  America,  83 — 91, 
earlier  and  later  migrations,  317 — 
320  ;  route  of  ancient  Tertiary  mi- 
gration, 328,  329  ;  antelopes  in 
America,  407 

Astacus  (see  Potamobius). 

Astrapotheria,  399 

Atalapha  (see  Lasiurus). 

Ateles  vellerosus,  250 

Athabasca  -  Mackenzie  region,  fauna 
and  flora  of,  58 — 73 

Atherina  evermanni,  290 

Atlantic  islands,  origin  of,  383 — 393 

Atlantic  States,  effect  of  moist  cli- 
mate on  vegetation,  167 

Atophyrax,  201 

Auckland  island,  earthworms  of,  424 

AUSTAUT,  Asiatic  origin  of  Apollo 
butterflies,  90 

Avocettula,  367 

"Axolotl,"  137 

B 

Bahamas,  raccoon  in,  181  ;  effect  on 
Gulf  Stream  by  elevation  of,  185 
(See  Antilles.) 


BAILEY,  distribution  of  Microtus,  28 

BANGS,  mammals  of  Labrador,  28  ; 
water-vole  of  Florida,  182 

BANGS  and  BRADLEE,  Bermudan  birds, 
188 

BANKS,  scorpions  of  Florida,  179 

B  ARBOUR,  on  alligators,  180  ;  Jamai- 
can reptiles  and  amphibians,  288  ; 
Bahama  reptiles  and  amphibians,  288 

BARRETT  -  HAMILTON,  external  cha- 
racters of  arctic  hare,  9 

BARRETT  -  HAMILTON  and  BONHOTE, 
varieties  of  arctic  fox,  11 

Bartonius,  177 

Bassaricyon,  249 

Bassariscus,  201 

BATES,  antiquity  of  forests  in  South 
America,  364;  on  Heliconiidae,  368; 
discovery  of  Cryptostemma,  369 

BAUR,  on  Galapagos  islands,  296;  Tro- 
fidurus,  311;  harmonic  and  dishar- 
monic  faunas,  311 — 313;  theory  of 
origin  of  Galapagos,  312  ; 
accounts  for  peculiarities  of  flora, 
315  ;  on  Indo  -  Pacific  continent, 
323 

Bear,  black,  28  ;  barren-ground,  61  ; 
in  Alaska,  80  ;  spectacled,  350 

Beavers,  extinct  in  Alaska,  80  ;  in 
lower  Pleistocene,  153 

BEDDARD,  connection  between  Pata- 
gonia and  the  Australian  region,  421 

Beetles,  distribution  of  running,  20  ; 
in  Scarboro'  Heights  deposit,  43  ; 
of  Eocky  Mountains,  117,  118  ;  of 
south  -  western  States,  215  ;  of  Old 
Calabar,  381  ;  of  St.  Helena,  387 

BELT,  connection  of  Atlantic  and 
Pacific  Oceans,  239  ;  birds  of  Cen- 
tral America,  250 

BENHAM,  faunistic  affinities  of  New 
Zealand, .  424 

BENTHAM,  floral  affinities  of  St. 
Helena,  391 

Berendtia,  206 

Bermuda,  183,  184  ;  geology  of,  184, 
186  ;  comparison  with  Bahamas, 
185;  flora  and  fauna,  186—194;  affi- 
nities of  fauna,  190 

BERRY,  Pleistocene  climate,  175  ;  mid- 
Cretaceous  floral  affinities,  414 


474 


INDEX 


BIGELOW,  Pacific  medusae,  240  ; 
absence  of  surface  forms  in  parts 
of  Pacific,  335 

Big-horn,  Kamchatkan,  85,  104,  105; 
Eocky  Mountain,  104,  105 

BINNEY,  distribution  of  Helix  hor- 
tensis,  14 

Birds,  geographical  distribution  of, 
61  ;  of  Nova  Scotia,  56  ;  of 
Mackenzie  Eegion,  61  ;  of  Rocky 
Mountains,  113  ;  of  Galapagos  is- 
lands, 301,  302  ;  of  Bermuda,  188, 
189  ;  of  Central  America,  250,  251; 
of  West  Indies,  290  ;  of  South 
America,  367—369 

Bison,  range  and  history  of,  65 — 67  ; 
in  Gulf  plains,  145 

Bison,  bison,  65;  sivalensis,  66;  alleni, 
66,  80  ;  scaphoceras,  66  ;  crassi- 
cornis,  67,  80;  prisons,  67;  occiden- 
tals, 80 

BLAISDELL,  Tenebrionidae,  215 

BLANFOHD,  permanence  of  ocean 
basins,  277  ;  on  volcanic  islands, 
297  ;  relationship  of  reptiles  and 
amphibians  of  South  America  and 
Africa,  374,  376 

Blanus,  375,  376 

Blaps,  215 

Blastocerus,  111 

Blastomeryx,  110,  112 

Blue-bird  in  Bermuda,  188 

Boas,  distribution  of,  203 

Boeckella,,  424 

BOETTGER,  Tertiary  Helices,  193  ; 
Helicidae,  affinities  of,  206  ;  on 
Adelopoma,  257  ;  Atlantic  Miocene 
land-bridge,  272  ;  connection  between 
Galapagos  and  Central  America,  313  ; 
Clausilia  of  South  America,  349  ;  Ter- 
tiary fossils  in  Amazon  valley,  360 

Boidae,  203 

Boltenia,  272 

Bombinator,  204 

BONHOTE  (see  BARRETT-HAMILTON). 

Bodtherium,  154;   bombifrons,  80,  154 

BORN,  distribution  of  running  beetles 
in  North  America,  20 

BOSE  and  TOULA,  fossils  of  Isthmus 
of  Tehuantepec,  238  ;  affinities  of 
Pacific  and  Atlantic  faunas,  24] 


BOULENGER,  distribution  of  Lygosoma, 
125  ;  on  Tropidonotus,  129  ;  affini- 
ties of  Emys,  134  ;  distribution  of 
Coecilians,  370  ;  distribution  of  Der- 
mophis,  377  ;  African  fishes,  378,  379. 

BOURGUIGNAT,  identity  of  European 
and  American  Clausilia,  272 

BOUVIER,  distribution  of  Onychophira, 
346, 369  ;  distribution  of  Peripatus,  432 

Bow-fin  in  Mississippi  basin,  163 

Brachionycha  nubeculosa,  214 

Brachydontes  magellanica,  428 

Brachylagus,  226 

Brachylophus,  207 

Brachymeles,  126 

Brachypodella,  267 

BRADLEE  (see  BANGS). 

Brady 'pus,  366 

Bradytherium    in    Madagascar,    366 

BRANDEGEE,  Californian  flora,  208 

BRANSFORD  (see  GILL). 

BRAUER,  arctic  fauna,  6 

BRAY,  plants  common  to  Andes  and 
Rocky  Mountains,  104  ;  floral  affi- 
nities of  North  and  South  America, 
415,  416 

Brazil,  363  ;  summary  of  geological 
history,  393—394 

BREHM,  Crustacea  of  Greenland,  19 

BRENDEL,  on  Florida  plants,  167 

Bridger  deposits  of  Wyoming,  102, 
143,  163,  229,  244 

BRITTON,  Flora  of  Antarctic  con- 
tinent, 422 

BROOKE,  structural  characters  of 
Cervus  canadensis,  68 

BROOKS,  great  range  of  climate  in 
Alaska,  74  ;  geology  of  Alaska,  84 

Brotulidae,  290 

BROWN,  A.  E.  dispersal  of  reindeer, 
5  ;  North  Atlantic  land-connection, 
25,  222  ;  Rocky  Mountain  sheep, 
104,  105  ;  origin  of  Oreamnos,  106; 
variation  of  garter-snakes,  128  ; 
origin  of  rattle  -  snakes,  131  ; 
centres  of  dispersal,  174 

BROWN,  B.,  age  of  Potter  Creek  de- 
posits, 29  ;  Conard  fissure,  61,  64, 
70,  87  ;  remains  of  mule-deer  from 
Conard  fissure,  108  ;  Symbos  and 
Scaphoceros,  155 


INDEX 


475 


BROWN,  K.,  similarity  of  Greenland 
and  European  reindeer,  4  ;  arctic 
hare,  9 

BROWN,  E.  N.  K.,  on  Diego  Alvarez, 
393 

BUOWN,   S.,  Bermudan  flora,   187 

BRUCE,  fossils  from  Falkland  islands, 
430;  soundings  in  southern  Atlantic, 
433 

Buckleyia,  256,   268 

BUDDE-LUND,  on  the  Pacific  Con- 
tinent, 320 

Budorcas,  106 

Buffalo  (see  Bison). 

Bufo,  absence  from  Jamaica,  288 

Bugs  of  St.  Helena,  388,  390 

Bulimus,   390 

Bulimulidae,   269—271,    273 

Bulimulus,  176,  206  ;  of  Lower  Cali- 
fornia, 208  ;  on  ancient  Pacific  land, 
209,  210  ;  of  Galapagos,  306—308  ; 
of  St.  Helena,  390  ;  common  to 
Chile,  Galapagos,  and  California, 
410  ;  forms  not  easily  distinguish- 
able, 269,  270  ;  americanus,  270  ; 
rldleyi,  270,  385 

Bunting  on  Diego  Alvarez,  293 

Buprestidae,  425 

BURCKHARDT,  C.,  on  Pacific  con- 
tinent, 427 

BURCKHARDT,  E.,  distribution  of 
flightless  birds,  423 

Burdwood  Bank,  429 

Butterflies,  dispersal  of,  115  ;  of 
south  -  western  States,  214  ;  of 
Antilles,  289  ;  of  Florida,  179 


Cactornis,  301 

Caenolestes  in  Santa  Cruz  beds,  350, 
404  ;  in  Ecuador,  350 

California,  geological  history,  198 — 
200  ;  Cape  Eegion  of,  199,  207  ; 
fauna  and  flora  of  Cape  Eegion,  207, 
208  ;  relationship  with  Europe,  211; 
geology  of  Cape  Eegion,  329,  330, 
356  ;  Cape  Eegion  a  part  of  Pacific 
land-be^;,  331  ;  animals  common  to 
Chile,  333,  410,  412,  413 

Calif ornian  islands  flora,  210  ;  pecu- 
liar species  of  Epiphragmophora, 


410  ;  relicts  of  Pacific  land-belt, 
418 

CALVERT,  dragon  -  flies  of  Central 
America,  258 

Camarhynchus,  301 

Cambaroides,  218—220 

Cambarus,  place  of  origin,  177,  178  ; 
dispersal  of,  218 — 220  ;  primaevus, 
220  ;  cubensis,  291,  292  ;  mexicanus, 
291 

Camel,  ancient  migrations,  86  ;  fossil 
in  North  America,  153  ;  camel-like 
animals  of  America,  origin  of,  406, 
407 

Camelidae,  86,   116,   406 

Camelus,  153 

CAMERANO,  cranial  differences  in  rein- 
deer, 5 ;  varieties  of  reindeer,  34 

CAMPBELL  (see  HAYES). 

Campylaea,  206 

Canadian  forest  region,  fauna  of,  63— 
67 

Cancer  amphiaetus ,  93,  94 

Canidae,  an  ancient  family,  149,  150 

Canis,  149,  150  ;  occidentalis  albus, 
61  ;  latrans,  149,  430  ;  dingo,  150; 
antarcticus,  430,  150  ;  tonggerana, 
150 

Capreolus,  resemblance  to  American 
deer,  111 

Caprolagus,  225 

Capr  ornery  x,  113 

Capromys,  282;    columbianus,  283 

Carabidae,  425 

Caraboctonus,  349,  350 

C  ambus,  supposed  accidental  distribu- 
tion, 20  ;  peculiar  distribution  in 
North  and  South  America,  235,  236, 
412,  413  ;  catenulatus,  20  ;  nemo- 
rails,  20 

Carcharhinus  nicaraguenxis,  241 

Carettochelyidae,  135 

Carcinocyon,  430 

Cardiastethus,  391 

Cardinal,  in  Bermuda,  188,  189 

Ca.rdina.lis   bermudianus ,   189 

Caribbean  Sea,  a  gulf  of  the  Pacific, 
241,  332 

Caribou,  derivation  of  name,  3  ; 
"  barren  -  ground,"  3,  5,  27,  58  ; 
"  wood-land,"  3,  5  ;  "  mountain,"  5 


476 


INDEX 


Carnivores,  Cretaceous  ancestors,   149 

CARPENTER,  Sonoran  region,  196,  197; 
Collembola  from  South  Orkneys,  433 

Carpodacus,  56 

CARTHAUS,  sea-water  formerly  more 
salt,  276 

Cascade  Mountains,    103 

Casmorynchus  niveus,  362 

Castor,  extinct  in  Alaska,  80 

Castoroides,  153,  285,  286 

Cat-bird,  in  Bermuda,  188,  189 

Cat-fish,   89,   361 

CATON,  likeness  of  wapiti  and  red- 
deer,  68 

Catostomus   rostratus,  89 

CAUDELL,  on  Phasmidae,  158 

Cebidae,  364 

Cebus,  364 

Celestas,  281 

Centetidae,  246,  282 

Central  America,  fannal  problems,  233, 
234  ;  geological  features,  237,  238 ; 
date  of  formation,  152  ;  time  of 
submergence,  241,  242  ;  elevated  in 
Pliocene  Period,  243  ;  flora  and 
fauna,  247—257  ;  affinity  with 
Europe,  257  ;  general  affinities  of, 
259,  260 

Centrums,  gracilis,  178  ;  carolimanus, 
178  ;  margaritatus,  178  ;  hentzi,  178 

Cephaloptems   ornatus,  362 

Cepolis,  175,  176 

Cercoleptes   flavus,  151,  248,  249 

Ceroglossus,  413 

Certhia,  56 

Certhidea,  315 

Cervalces,  32 

Cervidae,  origin  of,  109 — 111 

Cenmlus,  111 

Cervus,  origin  of,  68  ;  canadensis,  67 
— 69  ;  distinct  from  American  deer, 
107,  108 

CHAMBEELIN,  T.  C.,  and  SALISBURY, 
glaciation  of  Nova  Scotia,  41  ; 
interglacial  phases,  45  ;  ice  disper- 
sion from  Keewatin  centre,  46,  76, 
77 

CHAMBERLIN,  R.  V.,  North  American 
Lycosidae,  36 

Chamops,  127 

CHAPMAN,  origin  r,f  Antillean  fauna,  290 


Characinidae,  379,  380 

Chauliodes,  289 

Chelonians  of  north-eastern  States,  134 

Chelydridae,  134,  251,  319,  320 

Chelydra,  serpentina,  134  ;  rosignonii, 
135 

Chile,  395  ;  occurrence  of  northern 
forms,  234  ;  species  in  common  with 
California,  333,  334  ;  poverty  of 
freshwater  fauna,  405  ;  distribution 
of  mammals,  406  ;  species  in 
common  with  California  and  Gala- 
pagos, 410  ;  western  extension  of,  427 

Chilean   islands,    418 

Chilonopsis,   390 

CHILTON,  Antarctic  continent,  425 

Chinchilla,  353,  354 

Chipmunk,  63 

Choanopoma,  176 

Choloepus,  366 

Cholog  aster,  165 

Chondropoma,  175 

Chorophilus  nigritus,  31 

Chrosomus  erythrog aster,  50 

Chrysemys,  132 

Chrysochloridae,  245,   246,   404 

Chrysocyon,  430 

Chrysothrix,  364 

Chub,  silver,  in  drift  area,  51 

Cichlidae,  234,  290,  362,  379 

Cinclus,  origin  of,  113 

Cinosternidae,  362 

Cistudo,  134 

Citellus,  general  range  of,  60  ;  parryi, 
61,  85  ;  douglasi,  61  ;  tridecem- 
lineatus,  61  ;  buxtoni,  85  ;  osgoodi, 
92;  nebulicola,  92;  beringensis,  92; 
barrowensis,  92;  stonei,  92 

Clausilia,  range  and  geological  his- 
tory, 272,  273  ;  discontinuous  dis- 
tribution of,  348,  349  ;  pauli,  272, 
349 

Clemmys,  guttata,  132  ;  marmorata, 
133,  222  ;  leprosa,  133,  222  ;  in- 
sculpta,  133  ;  morrisiae,  133 

Coati,   of   western   origin,   249 

Cochlicopa  lubrica,  72 

COCKERELL,  distribution  of  Helix  hor- 
tensis,  14  ;  Florissant  shales  of  Mio- 
cene Age,  118  ;  Florissant  shales, 
200  (See  BOBBINS.) 


INDEX 


477 


Cocornis,   301 

COE,  land-nemertean  in  Bermuda,  191 

COE  and  KUNKEL,  Californian  limbless 

lizard,  202 

Coecilians,  251,  252,  370 
Coeciliidae,    geological    history,    251, 

252,  348 
Coendidae,  71 
Coendu,   migrations    of,    70,    71  ;     in 

Brazil,   366;    origin  of,  403 
C olios,  in  Kocky  Mountains,   117  ;   in 

southern      South     America,      235  ; 

nastes,  22 
Coleoptera    of  South  America  related 

to  those  of  Australia,  425 
Collembola  from  South  Orkneys,  433 
COLEMAN,    fossil    plants    as    tests    of 

climate,   43  ;     Canadian   Pleistocene 

flora,  44 
Columbigallina       bermudiana,      188   ; 

passerina,  188 
Conard  Fissure,  fauna  of,  61,  64,  70, 

107,  108,  153 
Condylura  cristata,  142 
Conepatus,  201 
Conolophus,  304 
Conoryctes,  244 
Conulus,  306,  308  ;  fdbricii,  21 
Conuropsis  carolinensis ,  159,  172 
Conurus,  172 

CONWENTZ,  distribution  of  musk-ox,  7 
COOK  (see  MATTHEW). 
COOKE,   A.    II.,   operculate   land-mol- 

lusks,  57 

COOKE,  W.  W.,  bird  migration,  168 
COOPER,  Californian  mollusks,  208 
COPE,    varieties   of   bison,    66  ;     Felis 

hillianus,      107  ;      distribution      of 

ground-lizard,   124  ;    mud-puppy  of 

eastern    States,    136  ;     eastern    and 

western     types     of     snakes,     173  ; 

Sonoran   region,    196  ;    fossil   voles, 

224  ;    fossils    of    Puerco   formation, 

244 

COPELAND,  flora  of  Trinidad,  396 
Corals,      fossil,     of     Barbados     with 

Mediterranean    affinities,    278 
Corydalis,   E89 
Cosoryx,  112 
Cotingidae,  362,  368 
Cougar,   vast  range  of,    106,    107 


COVILLE,  land-bridge  between  Asia  and 

North  America,  83 
Coyote,  distribution  in  North  America, 

149,     150  ;      related     to     Falkland 

Island  wolf,  430,  431 
Coypu,  distribution  and  ancestry,  282, 

283,  396 
Crabs,  distribution  of  freshwater,  255; 

of    Cuba,    291  ;    of   coast   of   Chile, 

333  ;  of  southern  South  America,  405 
CRAGIN,    fossil     species      of     Nemor- 

rhaedus,  106 
Crayfish,    freshwater,   distribution   of, 

217,  218  ;    of  south-western  States, 

218  ;     of    Cuba,    291  ;      of    South 

America,  405  ;     of  Chile  and  New 

Zealand,   420,   424,   426 
CREDNER,  fauna  of  relict  lakes,  49  t 
Creodonta,  373 
Crepidula  gregaria,   428 
Crocidopoma,   in  Antilles,   256,   268 
Crocodilus  americanus,  180,   181 
Crotalus,   131,   253  ;     horridus,    131  ; 

terrificus,  131,  253 
Crow  in  Bermuda,  188 
Crustacea,  of  the  Great  Lakes,  48,  49  ; 

blind,  of  Cuba,  291 
Cryptostemma  westermanni,  369,  370, 

382 
Cryptobranchus,    83  ;      allegheniensis , 

135  ;  japonicus,  135 
Ctenodactilus,  372 
Ctenodactylidae,  371 
Ctenomys,  brasiliensis,  371  ;   minutus, 

371 

Ctenosaura  hemilopha,  207 
Ctenucha,  214 
Cuba,    poverty   of   mammalian   fauna, 

261,    262  ;    cave   fauna,    285,    290  ; 

fishes,   290,   291 
Cubans,   pisum,    179  ;    galapagoensis, 

309  4 

Cucullaea  alia,  428 
Cupiennius  sallei,  178 
Curassows  in  Central  America,  250 
Curculiomdae,  391 
Cyclophis,   130,   319  ;    aestivus,   130 
Cyclophoridae,  256,  257,  268 
Cyclura,   207 

Cylindrellidae  (see  Urocoptidae'). 
Cynomys,  148,  149;   ludovicianus,  148 


478 


INDEX 


Cyprinids,  50 
Cyrtotoma,  256,  268 
Cystognathidae,  421 

D 

Dace,  red-bellied,  in  drift  area,  50 

DAHL,  distribution  of  spiders,  191  ; 
arctic  centre  of  dispersal,  427,  428 

DALL,  Helix  hortensis  in  Pleistocene 
clays,  14  ;  temperature  of  Pliocene 
seas,  16  ;  land  between  Asia  and 
North  America,  83  ;  fauna  of  north- 
east Pacific,  93  ;  subsidence  in 
Alaska  in  Pleistocene  times,  96; 
marine  gravels  at  Nome,  94  ; 
climate  during  Tertiary  Era, 
94 — 97  ;  on  Helicina,  158  ;  geo- 
logical history  of  Florida,  176  ; 
mollusks  of  Florida,  176  ;  Calif  or- 
nian  Bulimulus,  208  ;  Galapagos 
islands,  296  ;  importance  of  acci- 
dental distribution,  306,  307  ; 
Alaskan  leaf -bed,  318,  319;  Miocene 
mollusks  of  Penjinsk,  319  ;  marine 
faunal  provinces,  333,  334 

DALL  and  HARRIS,  Miocene  change  of 
Gulf  Stream,  186 

DALY,  geology  of  Labrador,  41 

Damon  variegatus,  382 

Damophila,  350 

Darien,  isthmus  of  (see  Central 
America) . 

DARWIN,  Galapagos  islands,  295—297  ; 
human  importations,  298  ;  birds  and 
lizards  of  Galapagos,  301—303;  flora 
of  Galapagos,  310  ;  subsidence  of 
Pacific  Ocean,  321,  322,  331  ;  Ascen- 
sion island,  386  ;  description  of 
Falkland  islands,  430,  431 

Dasychira  roseii,  36 

Dasypoda,  399,  40^ 

Dasyuridae,  183 

DAWSON,  G.,  foraminifera  in  Glacial 
clays,  47 

DAWSON,  J.  W.,  Pleistocene  flora  and 
fauna  of  Canada,  44,  53  ;  foramini- 
fera  in  Canadian  Pleistocene  clays, 
47  ;  views  on  Glacial  Epoch,  98 

DAVID,  atoll  boring  at  Funafuti,  321 

Deer,  origin  of,   109—111 


DENBURGH,  VAN,  lizards  of  Lower  Cali- 
fornia, 207  ;  reptiles  of  Galapagos, 
305  ;  reptiles  and  amphibia  of  Cali- 
fornian  islands,  418 

D&ndrobatidae,  377 

DEPERET,  pedigree  of  horse,  147  ; 
original  home  of  fossil  horses,  148; 
centres  of  origin,  227  ;  Miocene  and 
Pliocene  migrations,  230  ;  age  of 
Central  America,  243 

Dermatemydidae,  236,   251 

Dermatemys  mawi,  251 

Dermophis,  370,  376 

DE  SELYS,  Pitymys  from  St.  Gothard, 
223 

Devisia  mythodes,  135 

Diapheromera  femorata,  158 

Dibelodon,   231 

DICKERSON,  amphibians  of  Hudson 
Bay  region,  31 

Dicrocerus,  111 

Dicrostojiyx,  torquatus,  9 — 11  ;  hud- 
sonius,  11,  27,  60 

Didelphyidae,  229,  367,  403 

Didelphys,  182,  183  ;  marsupialis,  182, 
283,  366 

DIEDERICH,  distribution  of  magpies,  88 

Diego  Alvarez  island,  393 

DILG,  anatomy  of  manatees,  279,  280 

Dinosaurs,  400 

Dione,  179 

Diplocardia,  174 

Diplocynodon,  180 

Diplodon,  425,   426 

Diploglossus  (see  Celestus). 

Diplommatininae,  257 

Dipodomys,  201 

Dippers,  distribution  of,  113 

Discoglossidae,  204 

Discoglossus,  204 

DITMARS,  Sceloporus  undulatus,  126  ; 
remarks  on  rattle-snakes,  131  ;  re- 
marks on  terrapins,  132  ;  habits  of 
snapping  turtles,  134 

DODGE,  description  of  bison  herd,  65 

Dog,  wild,  of  Australia,  150  ;  of  Java, 
150 

Dolichonyx   oryzivorus,   301 

Dolichotis,  403 

D'ORBIGNY,  mid-Atlantic  land-bridge, 
359 


INDEX 


479 


Dragon  -  flies  of  Florida,  178  ;  of 
Central  America,  258  ;  of  Antilles, 
289 

DRASCHE,  boundaries  of  Pacific,  328 

Drift-deposit  in  North  America,  40 — 
43  ;  absence  of,  in  Labrador,  41 

Dromicus,  biserialis,  304;  chamissonis, 
304 

DBYGALSKI,  v.,  coast  lands  in  Green- 
land never  glaciated,  18 

Drymaeus,  175  ;  dominions,  176,  270; 
dormant,  270 


E 


EARLE,  tapiroids  in  Europe  and 
America,  353 

Earthworms,  in  Florida,  174  ;  affinity 
of  North  and  South  American,  412; 
importance  of,  in  zoogeography,  423, 
424;  of  Falkland  islands,  431 

Echimyinae,  372 

Echinoids,  fossil  of  America  and 
Europe,  278 

ECKEL  and  PAULMIER,  reptiles  of  New 
York,  123,  127 

Ecuador,  an  ancient  land-mass,  350  ; 
fauna  of,  354 

Edentates,  range  of,  152,  153,  156  ; 
origin  of,  244,  245  ;  in  Santa  Cruz 
beds,  399 

Eglandina,  175 

EIGENMANN,  on  blind  fish es,165;  fresh- 
water fishes  of  Central  America, 
253  ;  affinities  of  Cuban  fishes,  291; 
geological  history  of  South  America, 
340;  Orestias,  362;  land-bridge  be- 
tween Africa  and  South  America, 
379  ;  Patagonian  fishes,  405 

EISEN,  Cape  Region  of  Lower  Cali- 
fornia, 330 

Elateridae,  425 

Eleodes,  118 

Elodinae,  215 

Elephants,  remains  on  Pribilof  islands, 
78  ;  fossil  in  North  America,  153, 
200,  230,  231,  358,  359 

Elephas,  primi genius,  80;  cotumbi,  83, 


87,  153;   antiquus,  87;    meridionalis, 
87  ;   imperator,  87,  153 

ELLIOT,  black  musk-ox,  7 

EMERSON,  Texas  subterranean  newt. 
136 

EMERTON,  affinity  between  spiders  of 
America  arid  Europe,  23 

EMERY,  honey  ants,  216  ;  Formica  in 
America,  216 

Emydidae,  134 

Emys,  distribution  of,  51,  132 — 134; 
blandingi,  51,  132;  orbicularis,  51 

Enallagma,   178 

ENDERLEIN,  insects  of  south  Polar 
regions,  433,  434  ;  former  antarctic 
land-connection,  435 

Endodonta,  306,  308,  390  ;  helleri, 
308 

ENGELHARDT,  fossil  plants  of  Chile, 
414,  415 

ENGLER,  affinities  of  flora  of  Asia  and 
North  America,  93  ;  plants  common 
to  Andes  and  Rocky  Mountains, 
104  ;  affinities  of  western  Ameri- 
can plants,  139,  140  ;  origin  of 
Florida  plants,  168  ;  land-bridge 
between  South  America:  and  Africa, 
383  ;  St.  Helena  flora,  392  ;  Tristan 
da  Cunha  flora,  393  ;  floral  affini- 
ties of  North  and  South  America, 
415 

Entelops,  366 

Eohippus,  147,  228 

Epanorthidae,  350,  404 

Epihippus,  147 

Epilobocera,   255,   291 

Epiphragmophora,  206,  212,  410  ; 
tucumanensis,  411 

Erebia,  117 

Erethizon,  71,  366,  403  ;  dorsatus,  27, 
69  ;  epixanthum,  70 

Eryx,  203 

Eublepharus,   347 

Eucer  other  ium,  154 

Euchirotes,  207  ;   biporus,  202,  203 

Euconulus  fulvus,  72 

Eugenia,  350 

Eumeces,  123 — 126  ;  quinquelineatus , 
123,  189;  latiscutatus,  189;  longiros- 
tris,  189 

Eurymetopu'n,  413 


480 


INDEX 


Eustephanus  fernandensis,  418 

Eutenia  sirtalis,  127 

Eutoxeres,  350 

EVERMANN  (see  JORDAN). 

Evotomys,  29  ;   ungava,  27  ;   proteus, 

27  ;    wrangeli,   92  ;     dawsoni,   92  ; 

orca,  92 


Falkland  islands,  geology  of,  429,  430  ; 
fauna  and  flora,  431 

Faroe  Bank,  shells  dredged  off,   17 

FAXON,  crayfish,  218,  220 

Faxonius,  177 

Felts,  concolor,  107  ;   hillianm,  107 

Fernando  de  Noronha,  384,  385 

FERRIS,  mollusca  of  south  -  western 
States,  206 

Fiber,  obscurus,  56,  64;  zibethicus,  64, 
92  ;  spathulatus,  64,  92  ;  annectens, 
64. 

FEILDEN  and  DE  RANGE,  banded  lem- 
ming in  Greenland,  11  ;  glacio- 
marine  deposits,  47 

Florida,  flora  of,  167  ;  relation  to 
Antilles,  168  ;  former  geological 
conditions,  168—172  ;  fauna  of,  175 
— 182  ;  majority  of  faunal  elements 
non-tropical,  181,  182  ;  course  of 
Gulf  Stream  across,  185 

Florissant  Shales,  insects  and  plants 
of,  118,  200 

Flying  squirrel,  distribution  of,  63 

Foramiinifera,  in  boulder  clay,  41 

FORBES,  relationship  of  Madagascar 
and  South  America,  375  ;  Antarctic 
continent,  421 

Forest  region  of  North  America,  fauna 
of,  31,  63 

Formica,  cineria,  216  ;  rufibarbis,  216 

Fox,  arctic,  11,  27  ;  red,  27  ;  New- 
foundland, 56 

FRAZER,  Archaean  land  mass  in  Carib- 
bean Sea,  177 

Frogs,  near  Hudson  Bay,  31  ;  Florida 
tree,  173  ;  in  South  America,  377 

Funafuti,  boring  coral  reef  at,   321, 

322 

FURLONG,  Euceratherium  in  Cali- 
fornian  cave,  154 


GADOW,  affinities  between  reptiles  of 
Madagascar  and  America,  126  ;  dis- 
tribution of  salamanders,  137,  138  ; 
distribution  of  Scaphiopus,  205  ;  age 
of  genus  Spelerpes,  221  ;  home  of 
Coeciliidae,  251,  252  ;  geological 
history  of  Antilles  and  Central 
America,  287  ;  origin  of  Galapagos 
tortoises,  313  ;  on  Dendrobatidac, 
377 

Gaeotis,  271 

Galapagos  islands,  origin  of  fauna  and 
flora,  295—317 

Galaxiidae,  421 

Galeoscoptes  bermudianus,  189 

Gallinula  galeata,  188 

Gallinule,  Florida,  188  ;  on  Diego 
Alvarez,  393 

Ganodonta,  244 

Ganoid  fishes,  of  Mississippi,  88,  89, 
163,  164 

GARDINER,  beetles  of  White  Moun- 
tains, 37 

GARMAN,  H.,  on  blind  fishes,  165 

GARMAN,  S.,  Bermudan  skink,  189  ; 
reptilian  fauna  of  Galapagos,  303 

Garnieria,  273 

Gastrodonta,  193 

GAUDRY,  affinity  of  Patagonian  extinct 
fauna  with  that  of  New  Mexico  and 
France,  402 

Gecko  in  Galapagos  islands,  303 

Geckonidae,  303,  304 

GEIKIE,  A.,  on  permanence  of  ocean 
basins,  274,  276 

GEIKIE,  J.,  Greenland  in  Ice  Age,  18  ; 
inter-glacial  phases,  45  ;  gigantic 
glaciers  in  Ice  Age,  69 

Geoemyda  punctularia,  347 

Geomalacus,  213 

Geonemertes  agricola,  191 

Geospiza,  315 

GIDLEY,  Pleistocene  species  of  E quits, 
146,  147  ;  on  fossil  raccoon,  152 

"  Gila-monster,"  201 

GILL,  distribution  of  mud-minnows, 
51  ;  land-bridge  between  Asia  and 
America,  83,  88;  fishes,  as  indicators 
of  changes  of  land  and  water,  377, 


INDEX 


481 


378  ;  southern  continental  land  con- 
nections, 420,  423 
GILL     and     BEANSFOED,     fishes      of 

Nicaragua,  240 
GILMOEE,     Pleistocene     deposits      in 

Alaska,  79,  80 

GIEARD,  moths  common  to  Canada  and 
Europe,  22 

Glacial  Epoch,  survival  of  life  in 
Greenland  during,  18 — 25;  elevation 
of  land  in,  14,  42,  98  ;  cause  of,  15, 
99,  318  ;  mild  climate  in  northern 
latitudes,  19,  24,  43—46,  81,  154— 
157  ;  effects  of,  on  animals  and 
plants,  37 — 45  ;  survival  of  species 
in  drift  area,  36,  40,  41,  52  ;  in 
Newfoundland,  41,  55  ;  in  Nova 
Scotia,  56  ;  not  caused  by  diminu- 
tion of  temperature,  76,  156  ;  in 
Alaska,  76 — 79,  81  ;  in  Siberia,  81, 
82  ;  its  influence  on  fauna  and  flora, 
175  ;  inter-glacial  epochs,  45 

Glandina,  fossil  in  Florida,  171  ;  in 
Europe,  271,  272 

Glaresis,  215 

Glauconia,  dulcis,  203  ;  humilis,  203 

GlauGoniidae,  203 

Glutton  in  Labrador,  27 

Glyptodontia,  399 

Glyptotherium,  153 

Gnathocerus  maxillosus,  215 

Goat-antelopes,  106 

Goat,  Rocky  Mountain,  104—106 

GODMAN  and  SALVIN,  researches  on  the 
fauna  and  flora  of  Central  America, 
246  ;  Central  American  insects,  258 

Gonatodes,  304 

GOODEICH,  on  Ceratodidae,  379 

Gophers,  distribution  of,  60 

Gough  island  (see  Diego  Alvarez). 

GOULD,   Pacific   continent,    321 

GEABAU,  geological  history  of  Great 
Lakes,  54,  55 

Grandala,  188 

GEANDIDIEE,  on  Brady therium,  366 

GEANGEE,  on  Eocene  horses,  147 

GEANT,  varieties  of  reindeer,  3  ;  nor- 
thern land-connections,  25  ;  range 
of  moose,  32  ;  Rocky  Mountain  goat, 
105 

Gravigrada,  244,  399 

L.A. 


GEAY,  affinities  of  flora  of  Asia  and 
America,  92,  139  ;  Rocky  Mountain 
flora,  103  ;  North  and  South  Ameri- 
can plants,  415 

GEEENE,  flora  of  Californian  islands, 
210,  329 

Greenland,  flora  and  fauna,  3 — 22  ; 
land-connections,  12,  13,  30  ;  sur- 
vival of  species  in  Pleistocene  times, 
18—21  ;  former  climate,  19  ;  affini- 
ties with  Labrador,  42 

GEEENMAN  (see  ROBINSON). 

GEEGOEY,  elevation  of  Florida,  170  ; 
junction  of  Atlantic  and  Pacific, 
239,  241,  242  ;  land  -  connection 
between  North  and  South  America, 
264  ;  abysmal  deposits  in  Barbados 
and  Cuba,  277  ;  on  fossil  sea- 
urchins,  278  ;  on  fossil  corals,  278 

GEENFELL,  description  of  Labrador,  27 

GEOTE,  noctuids  common  to  Europe 
and  North  America,  22  ;  effect  of 
Glacial  Epoch  on  range  of  butter- 
flies, 38,  39 

Ground-dove,  in  Bermuda,  188 

Gryllus  bermudensis,  189 

Grypotherium  listed,  400 

Guadalupe,  flora  of,  417 

Guatemala,  flora  of,  247 

Guestieria,  348 

Guiana,  as  centre   of  dispersal,   362 

"Gulf  Plains,"  144 

Gulf  Stream,  course  in  Tertiary  times, 
185,  186 

GULICK,  Bermudan  fossil  mollusca,  193 

Gulo  luscus,  27,  61 

GUNTHEE,  Central  American  fishes, 
240  ;  reptilian  fauna  of  Galapagos, 
303  ;  land  isopod  from  Galapagos, 
309  ;  distribution  of  fishes,  378  ; 
fauna  of  Ascension,  386 

GUPPY,  H.  B.,  on  Pacific  continent, 
324 — 326  ;  mangrove  formation,  333 

GUPPY,  R.  J.  L.,  mid- Atlantic  land- 
bridge,  278 

Gymnocephalus  calvus,  362 

H 

HAACKE,  Polar  origin  of  life,  23,  428 
HACKEL,  affinities  of  North  and  South 
American  floras,  415,  417 
I  I 


482 


INDEX 


Eadruroides,  349,  350 

Hadrurus,  349,  350 

Halichoerus,  280 

HANDLIRSCH,  on  fossil  insects,  118, 
158,  391  ;  fossil  Liometopum,  216 

HANSEN,  distribution  of  Koenenia,  217 

Hapalidae,  364 

Haplarmadillo,  190 

Haplophora,  258 

Hare,  range  of,  224 — 226  ;  arctic,  9, 
10  ;  fossil  of  England,  10  ;  Irish, 
10  ;  in  Mackenzie  Kegion,  59;  Cape 
jumping,  372,  373  ;  Patagonian,  396 

HARRIS  (see  DALL). 

HARRISON,  Mackenzie  Eiver,  58 

HARSHBERGER,  effects  of  Glacial  Epoch 
on  flora,  39,  40  ;  flora  of  Florida, 
168,  169  ;  Bermudan  flora,  187 

HARTERT,  on  humming-birds,  350,  367 

HARTERT  (see  KOTHSCHILD). 

HATCHER,  on  American  palaeontology, 
102 

HAUG,  on  Pacific  continent,  327 

HAY,  origin  of  fossil  turtles,  133,  134, 
251  ;  climate  of  Pleistocene  Period, 
154—156 

HAYES  and  CAMPBELL,  change  of  river 
courses,  162,  163 

HEBARD  (see  KEHN). 

HEDLEY,  north  Atlantic  land-connec- 
tion, 30  ;  Placostylus,  209  ;  Pacific 
land  -  connections,  323,  324  ;  ant- 
arctic land-connection,  421,  422 

HEILPRIN,  origin  and  migration  of 
animals,  97  ;  Bermuda  islands,  186; 
Antarctic  continent,  422 

Helicidae,  193,  205,  212 

Helicigona,  212,  411 

Helicina,  192,  306,  308  ;   chrysocheila, 

157  ;    orbicula,   157  ;    occulta,   157, 

158  ;   convexa,  192,  193 
Heliconiidae,  368 

Heliconius,  179  ;    charitonia,  368 
Helix,   hortensis,   distribution   of,    13, 

14,  39,  141  ;   in  Labrador,  30  ;   in 

Pleistocene  clay  of  Maine,  39  ;  im- 

bricata,  193 

"  Hell-bender,"  135,  319 
HELLER,  mammalia  of  Galapagos,  299; 

reptiles    of    Galapagos,    303,    304  ; 

geological  age  of  Galapagos,  305 


HELLER  (see  SNODGRASS). 

Heloderma,  202 

Hemiauchenia,  406 

Hemiptera,  common  to  Europe  and 
America,  89,  90  ;  of  St.  Helena,  388 

Hemphittia.,  212 

HEMSLEY,  Bermudan  flora,  187  ;  Cen- 
tral American  and  Mexican  floras, 
246 — 248  ;  on  origin  of  Galapagos 
islands,  315 

Her os,  tetracanthus,  290  ;  nigricans,  290 

Herpele,  370 

HERSHEY,  ancient  land  west  of 
Panama,  331 

Hesperarion,  212 

Hesperomys,  298 

Hexura,  412 

HILL,  orogenic  movement  in  Antilles, 
171;  geology  of  Panama,  236 — 238; 
east  coast  of  America  in  pre-Cre- 
taceous  times,  263,  264  ;  sunken 
land  west  of  Central  America,  331 

HINTON,  origin  of  arctic  hare,  10 

Hipparion,  148 

Hoatzin,  362 

Hodomys,  201 

HOLDHAUS,  on  Pacific  continent,  324 

HOLLICK,  east  American  flora,  140,  141 

HOLLISTER,  on  musk-rats,  64 

Holospira,  206 

Homalota,   391 

Homo  cubensis,  285 

Homunculidae,  365 

HOOKER,  survival  of  plants  in  Green- 
land, 17  ;  Kocky  Mountain  flora, 
103  ;  Asiatic  floral  element  in  North 
America,  139  ;  floral  affinities  of  St. 
Helena,  391  ;  former  antarctic  land- 
connections,  420 

HORNADAY,  extermination  of  bison,  65 ; 
habits  of  Kocky  Mountain  sheep,  105 

"  Horned- toad,"  great  antiquity  of, 
202 

Horses  in  America,  extinction  of,  146; 
geological  history,  146,  148,  228 

HORVATH,  Hemiptera  common  to 
Europe  and  North  America,  89,  90 

HOWARD,  spread  of  species  by  agency 
of  man,  65 

HOWORTH,  level  of  land  in  Pleistocene 
times,  15  ;  temperate  climate  in 


INDEX 


483 


Arctic  regions,  19  ;  mild  climate 
during  Glacial  Epoch,  46;  Forami- 
nifera  in  glacial  clays,  47;  water  as 
agent  in  formation  of  glacial  de- 
posits, 77  ;  past  climate  of  Siberia, 
81  ;  range  of  mammoth,  86 

HOY,  on  Mysis  relicta  in  Lake 
Michigan,  48 

Huanaco,  distribution  of,  406 

HUDSON,  on  pampas  of  Argentina,  396, 
397 

Hudson  Bay  region,  31 — 36  ;  invaded 
by  waters  of  Arctic  Ocean,  47 

HULL,  pre-Glacial  elevation  of  land, 
14 

Humboldt  Current,  striking  Galapagos 
islands,  294,  300  ;  did  not  exist 
during  Tertiary  Era,  334,  335 

Humming-birds,  range  of,  250,  367, 
368 

Hutia  in  Antilles,  282 

HUTTON,  on  Pacific  land-connections, 
322,  420,  426 

HUXLEY,  on  cray-fish,  218 

Hyalinia,  radiatula,  72;  nitidula,  72; 
cellaria,  389  ;  alliaria,  389 

Hyalinia  (see  Vitred). 

Hyla  gratiosa,  173 

Hymenochirus,  377 

Hymenoptera,  wingless  of  Australia 
and  South  America,  433 

Hyracotherium,  147 

Hysiricidae,  71 

Hystricomorpha,  371 — 373  ;  in  Santa 
Cruz  beds,  399,  402 


Iguanavus,  127 

Iguanidae,  126,  202,  207,  304,  305 
IHERING,  v.,  affinities  of  Phlaocyon, 
151,  152  ;  origin  of  Procyonidae* 
152  ;  dispersal  of  mollusks,  161  ; 
on  Mutelidae,  161  ;  range  of 
Helicidae,  205,  206,  212;  distribution 
of  Unionidae,  254;  Archhelenis,  '274; 
on  origin  of  Galapagos  islands, 
313  ;  Pacific  Continent,  322  ;  fossil 
marine  mollusks  of  South  America, 
334  ;  researches  in  South  America, 


337  ;  freshwater  mussels  of  Brazil 
and  Africa,  338  ;  palaeogeography 
of  South  America,  339,  340  ;  dis- 
tribution of  Clausilia,  349  ;  origin 
of  South  American  bear,  351  ;  South 
America  in  Eocene  Period,  362;  ; 
land-connection  between  Africa  and 
America,  380  ;  flora  of  South 
America,  383  ;  Fernando  de 
Noronha,  385  ;  flora  of  St.  Helena, 
392  ;  dispersal  of  wolves,  396  ;  dis- 
tribution of  freshwater  mussels  in 
South  America,  405  ;  on  age  of 
Santa  Cruz  beds,  398  ;  relationship 
of  west  American  and  European 
shells,  411  ;  faunistic  affinities  of 
Chile  and  New  Zealand,  420,  421  ; 
dispersal  of  marine  mollusks,  428, 
429  ;  affinities  of  Falkland  island 
wolf,  430 

Insectivora,  of  eastern  States,  141, 
142  ;  of  Bridger  deposits,  143  ;  of 
south-western  States,  201  ;  of  Santa 
Cruz,  399 

Insects  from  Antarctic  regions,  433, 
434 

lonolaema,  350 

Ischyromidae,  228 

Isectolophus,  353 

Isometrus  maculatus,  389 


JACOBI,  connection  between  Australia 

and  South  America,  421 
Japyx,  411  ;    solifugus,  411  ;    subter- 

raneus,  412  ;  saussurei,  412 
JOHANSEN,  subsidence  of  land  tested 

by  marine  shells,  17 
JOHNSON,   distribution   of   Helix  hor- 

tensis,  14 
JOLY,  on  permanence  of  ocean  basins, 

275,  276 

JONES,   submarine    deposits    in    Ber- 
muda, 184 
JORDAN    and    EVEEMANN,    origin    of 

North  American  blind  fishes,  165 
JORDAN,  Central  American  fishes,  240 
Juan  Fernandez  island,  418 

n2 


484 


INDEX 


Kangaroo-rats  of  western  States,  201 

KARSCH,  on  Cryptostemma,  370  ;  dis- 
tribution of  Japyx,  412 

KATZER,  geology  of  South  America, 
342—344,  360 

Keewatin  ice-sheet,  73,  77 

KENNARD  and  WOODWARD,  post-Plio- 
cene mollusca,  21 

Kerria,  208,  412 

Kessleria,  88 

Kingsleya,  255 

Kinkajou  in  Mexico,  248 

KNOPF,  land-connections  between  Asia 
and  North  America,  84,  319 

Koenenia,  412  ;  draco,  217  ;  mirabilis, 
217  ;  wheeleri,  217 

KOKEN,  geology  of  South  America,  343 

KOLBE,  distribution  of  Enallagma, 
179  ;  distribution  of  beetles,  215  ; 
Antillean  dragon-flies,  289  ;  South 
Atlantic  land-bridge,  381  ;  antarctic 
land-connection  as  shown  by  beetles, 
425,  432 

KOBELT,  Helicidae,  206  ;  distribution 
of  Cyclophoridae,  257,  268  ;  affini- 
ties of  European  and  Antillean  mol- 
luscan  faunas,  271  ;  zoogeography 
of  St.  Helena,  389 

KOWARZIK,  structure  of  musk-ox,  7, 
8  ;  musk-ox  of  Mackenzie  region, 
59  ;  the  genus  Ovibos,  154 

KRAEPELIN,  Scolopendridae  from  Cali- 
fornia and  southern  Europe,  217  ; 
distribution  of  Damon  variegatus, 
382 

KRISHTAFOVITCH,  North  Atlantic  land- 
connections,  25 

KUNKEL  (see  COE). 

"  Kuroshiwo  "  current,  94,  95,  318 


Labrador,  26,  27  ;  flora  and  fauna, 
26 — 31  ;  connection  with  Greenland, 
30  ;  affinities  with  White  Mountains, 
42 

Lachesis,   131 


Lagopus,  62  ;  albus,  62  ;  rupestris, 
62  ;  leucurus,  62  ;  scoticus,  62  ; 
mutus,  62  ;  hypcrboreus,  62 

Lagidium,   353 

Lagomorpha,  224 — 226 

Lagostomidae  (see  Viscaciidae). 

Lakes,  Great,  of  North  America,  in- 
vaded by  the  sea,  47  ;  fauna  of,  49, 
50  ;  geological  history  of,  50,  54 

Lama  huanachus,  406 

LAMPLUGH,  on  inter-glacial  epochs,  45 

Lampsilis,  254  ;  borealis,  52  ; 
superiorensis,  52 

Land-connection,  north  Atlantic  (be- 
tween Scotland,  Greenland,  and 
Labrador),  12—25,  30  ;  mid- Atlan- 
tic (between  southern  Europe  and 
West  Jndies),  203,  271—281,  293, 
294,  309  ;  mid-Atlantic  (between 
southern  Europe  and  south-western 
North  America),  110,  114,  120,  164, 
173,  203,  204,  211—230,  366—380  ; 
south  Atlantic  (between  eastern 
South  America  and  west  Africa), 
110,  282,  338—340,  366—385,  389, 
390,  392,  394;  south  Atlantic  (be- 
tween Patagonia,  South  Africa,  and 
Madagascar),  344,  372,  375,  404,  405, 
429—433  ;  north  Pacific  (Bering 
Strait),  5,  12,  28,  29,  32,  61—71,  62 
—97,  115  ;  north  Pacific  (between 
western  North  America  and  eastern 
Asia),  202,  318—329,  407,  408  ; 
Pacific  belt  (between  North  and 
South  America  westward  of  Central 
America),  71,  245,  246,  254,  316,,  317, 
329—335,  347,  356—358,  401—403, 
408—418,  431  ;  Antarctic  (between 
Patagonia  and  Chile,  and  Australia 
and  New  Zealand)  339—342,  403, 
404,  419—429,  433—435  ;  Atlantic 
(between  Bermuda  and  West 
Indies),  183,  205 
Land-nemertean  in  Bermuda,  191 
LANKESTER,  on  extinct  animals,  400 
LAPPARENT,  geology  of  South  America, 
342 

Lasiurus,     299  ;      brachyptis,     299  ; 

semotus,  300 

LECHE,  origin  and  age  of  Centet-idae, 
282 


INDEX 


485 


LECOQ,  glaciers  produced  by  high  tem- 
perature, 45 

LEIDY,  American   palaeontology,   102 

Lemming,  arctic,  9,  11  ;  in  Mackenzie 
region,  60 

Lemming-voles,    15  ;    range    of,    28 

Lemmus,  60  ;  trimucronatus,  60  ; 
minusculus,  60,  92  ;  nigripes,  60*, 
92  ;  lemmus,  60 

Leonia,  272 

Lepidoptera  of  Greenland,  22  ;  of 
White  Mountains,  36 ;  of  Alaska,  90, 
91  ;  of  Eocky  Mountains,  115  ;  of 
Antilles,  289 

Lepidosiren,  378 

Lepidosirenidae,  378,  379 

Lepidosteus,  163,  164,  290  ;  osseus, 
163,  164;  tropicus,  164;  tristoechus, 
290 

Leporidae,  224—226 

Leptinaria  (see  Tornatellina). 

Leptomeryx,    110 

Leptotherium,  113 

Leptotrichus  granulatus,  190 

Lepus,  225,  226  ;  variabilis,  9  ;  bangsi, 
56  ;  othis,  92  ;  poadromus,  92 

Lerma  River,  fish  fauna  of,  232 

Letourneuxia,  213 

Lichanura,  203  ;    trivirgata,  203,  207 

Liguus,  175  ;  fasciatus,  176 

Limnaea,  vahli,  21  ;  holbolli,  21  ; 
palustris,  2  ;  stagnalis,  72  ;  £rww- 
catula,  72 

Limnolagus,  225,  226 

Limnophylidae ,   413 

Linopodes,  258 

Liometopum,  216  ;  apiculatum,  216  ; 
micro cephalum,  216  ;  lindgreeni,  216 

Liopelma,  204 

Liopeltis  vernalis,  130 

Liparis,   307 

Lithobius,  pravocator,  189  ;  bermu- 
densis,  189 

Litopterna,   399 

Littorina  littorea,  16 

Lizards,  scarcity  of,  in  eastern  States, 
123  ;  abundance  in  western  States, 
196  ;  Bermudan,  189  ;  in  California, 
207  ;  in  Galapagos,  302—304  ;  in 
South  America,  369  ;  blue-tailed, 
123,  125  ;  burrowing,  202,  203  ; 


swift,  123  ;  ground,  124  ;  limbless, 
202 

Llama,  406 

LOBLEY,  north  Atlantic  land-connec- 
tion, 25 

LOCARD,  on  Clausilia,  272 

LONNBERG,  structure  of  reindeer,  4 

Lophiodontidae ,  353 

LOVEN,  marine  relicts  in  freshwater 
lakes,  48 

Loxia,  56 

Loxocemus  bicolor,  320 

Loxomylus,  267 

Lucanidae,  425 

LUCAS,  fossil  bisons  of  North  America, 
66;  land-connection,  Asia  and  North 
America,  83  ;  fossil  sheep  in  Ni- 
caragua, 105 

Lucifuga  subterraneus,  290 

Lumbricus  castaneus,  39 

Lutra  degener,  56 

Lychas  maculatus  (see  Isometrus). 

Lyciscus,  430 

LYDEKKER,  varieties  of  reindeer,  3,  4  ; 
musk-ox  from  Greenland,  7  ;  extinct 
bison,  67  ;  relationship  of  wapiti 
to  Siberian  maral,  68  ;  origin  of 
American  deer,  109,  110  ;  age  of 
Falkland  islands,  151  ;  origin  of 
opossums,  183,  367  ;  origin  of  Cen- 
tral America,  243  ;  affinity  be- 
tween African  and  American  faunas, 
371  ;  Falkland  island  wolf,  430 

Lygosoma  laterals,  124,  125,  319,  320 

Lynx  subsolanus,  56 

LYON,  on  hares  and  their  allies,  225 


M 


Mabuia,  376  ;   punctata,  376,  385 

MACFARLANE,  mammals  of  north-west, 
58 

Mackenzie   River,   58 

Macroclemmys  temminckii,  135 

Macrop-teryx,  368 

Macrorhaphis,   390 

Macrorhinus  leoninus,  428 

Macquarie  islands,  earthworms  of,  424 

MADDREN,  life  in  Alaska  during  Pleis- 
tocene times,  78,  79 


486 


INDEX 


Magellan  flora,  affinities  of,  417,  418 

Magpies,  distribution,  87,  88 

MAJOR,  FORSYTH,  meadow-voles,  224  ; 

on    Lagomorpha,    224  ;     on    fossil 

Leporidae,  225,  226 
Malacoclemmys  centrata,  132 
Mammoth  in  Alaska,  78—80,  87  ;    in 

Siberia,  82 
Manatees  on  both  sides  of  Atlantic, 

279,  280 
Manculus,  172 
Manidae,  373 
Mani*,  372 
Mantispa,  289 
Maral  deer,  68 
Margaritana  margaritifer,  distribution 

of,  34,  37,  51,  52,   55  ;    on  Pacific. 

slope  of  North  America,   162 
Marmoset,  364 
MARSH,  fossil  bison,  66  ;   progenitors 

of  Cervidae,  110 
Marsupials,  geological  history  of,  182, 

183,  366  ;    affinities  of  Patagonian, 

403 

Marten  in  Newfoundland,  56 
MARTENS,      mollusca       of       Central 

America,  256 

MARX,  Bermudan  spiders,  191 
Massoutiera,  372 
Mastodon,  70,   87,   153,   358  ;    advent 

in  America,  408,  409  ;    americanus, 

80  ;  chilensis,  408  ;  bolivianus,  408; 

andium,  408 
MATTHEW,     land-connection     between 

Asia  and  North  America,  84  ;    an- 
cestry  of  Odocoileus,  110  ;    insecti- 

vores     of     middle     Eocene,     143  ; 

Eocene  and  Miocene  carnwora,  149 

— 151  ;     junction    of    Florida    and 

Cuba,    171  ;       Lagomorpha,     226  ; 

fossil    rodents,    228  ;     Apternodus, 

246  ;  fossil  edentate  in  Cuba,  285  ; 

Mascall  beds  of  Oregon,  358 
MATTHEW  and  COOK,  antelope  remains 

in  Nebraska,  407 
MCLACHLAN,  distribution  of  Limnophi- 

lidae,  413 

Mecicobothriidae,  412 
MEEK,     Lerma     River     fishes,     232  ; 

Nicaraguan  fishes,  240 
Megalobatrachus,    135 


Megalocnus,   293 

Megalomastoma,  269 

Megalomys  (see  Moschophoromys). 

Megalonyx,  70,  87  ;  in  Miocene  of 
North  America,  152,  153  ;  in  drift 
area,  156  ;  in  Pliocene  of  Texas, 
235  ;  in  Oregon,  358 

Megarhaphis,  388,  390 

Megascolecidae,  412 

Megatherium  in  Patagonia,  400 

Meleagris,  galloparo,  159 

Meridogastra,  370 

Meristhus  scrobinula,  321 

MERRIAM,  C.  H.,  on  Synaptomys,  28  ; 
destruction  of  life  in  Glacial  Epoch, 
34  ;  prairie  fauna,  148,  149  ;  fauna 
of  southern  Florida,  175  ;  Sonoran 
region,  196,  197 

MERRIAM,  J.  C.,  Asiatic  antelopes  in 
America,  407 

MERRILL,  on  Lower  California,  207 

Merycodontinae,  112 

Merycodus,  112 

Mesohippus,  147 

Mesolama,  406 

Metacanthus  concolor,  391 

Metacheiromys,  401 

Metoponorthus  sexfasciatus,  190 

Mexico,  eastern,  relationship  of  fauna, 
198  ;  geological  history,  199,  200; 
relicts  in  west,  232  ;  flora  of  south, 
247 

Miacidae,  149—151 

MICHAELSEN,  distribution  of  earth- 
worms, 431 

Microbiotherium,  403 

Microphrys  platysoma,  333 

Microsauri,  304 

Microtus,  range  of,  28 — 64  ;  enixus, 
27,  28  ;  pennsylvanieus,  27,  28  ; 
terraenovae,  56  ;  operarius,  92  ; 
unalascensis,  92  ;  hadiacensis ,  92  ; 
yakutatensis,  92  ;  sitkensis,  92;  in- 
nuitus,  92  ;  abbreviatus,  92  ;  alleni, 
182 

Milax   (see   Amalia) . 

MILLER,  mammals  of  White  Moun- 
tains, 37  ;  meadow-voles,  224 

MILNE-EDWARDS,  on  antarctic  pro- 
blem, 423 

Miohippus,  147 


INDEX 


487 


Miolania,  404 

Mississippi,  fishes  of,  88,  89,  163  ; 
drainage  area,  144  ;  description  of 
its  course,  160 

Mites  of  Central  America,  258 

Moeritherium,  358 

Mole,  142,;,  star-nosed,  142  ;  fossil, 
143  ;  golden,  245,  246,  404 

Mole-mice,  201 

Mole-shrew,  201 

Mollusks,  land  and  freshwater,  in 
Hudson  Bay  Region,  37  ;  slow  dis- 
persal, 52  ;  as  illustrating  geogra- 
phical changes  in  North  America, 
51 — 54  ;  common  to  Alaska  and 
Asia,  83  ;  of  Florida,  175  ;  of  Ber- 
muda, 191 — 194  ;  of  south-western 
States,  205,  206  ;  of  Central 
America,  256,  257  ;  of  Antilles, 
265—274  ;  of  St.  Helena,  389, 
390  ;  marine,  absence  of  from 
relict  lakes,  49  ;  Pacific,  affinity  to 
English  Crag  species,  96  ;  of  West 
Indies  and  Mediterranean,  278  ;  of 
western  South  America,  333,  334  ; 
common  to  Patagonia  and  New  Zea- 
land, 428 

Monachus,  albiventer,  280  ;  tropicalis, 
280 

Monkeys,  distribution  of,  249,  250  ;  in 
Santa  Cruz  beds,  400  ;  capuchin, 
364  ;  squirrel,  364  ;  sakis,  364  ; 
spider,  364  ;  howlers,  364 

Moose-deer,  32,  33,  80,  92  ;  former 
range,  33  ;  absent  from  Newfound- 
land, 56  ;  in  Mackenzie  region,  67 

MORCH,  mollusks  of  Greenland,  21 

MORENO  and  WOODWARD,  Neomylodon 
listai,  400 

Morphidae,  368,  369 

MORSE,  discovery  of  Helix  hortensis, 
15  ;  dispersion  of  European  species 
on  American  shores,  16 

Moschophoromys,  desmaresti,  284  ; 
luciae,  284 

MOSELEY,  on  Bermudan  flora,  187 

Mouse,  red-backed,  29  ;  jumping,  29  ; 

in  Galapagos,  297 
Mud-minnows  in  drift  area,  51 
"  Mud-puppy,"  136 
MURRAY,    A.,     origin    of    Galapagos 


fauna,  311  ;  on  beetles  common  to 
Asia  and  America,  321  ;  on  south 
Atlantic  land-bridge,  381 

MURRAY,  J.,  on  coral  reefs,  327 

Mus,  sylvaticus,  24  ;  galapagoensis, 
297  ;  decumanus,  298  ;  rattus,  298 

Musk-ox,  present  and  former  range, 
6 — 9  ;  variations  of,  7  ;  place  of 
origin,  7,  8  ;  remains  within  drift 
area,  43  ;  in  Mackenzie  region,  59  ; 
in  Alaska,  78,  80 

Musk-rat,  64,  153 

Mussels,  freshwater,  51 — 55  ;  import- 
ance of  their  distribution,  160 — 
162  ;  of  Central  America,  254  ;  affi- 
nity between  African  and  Brazilian, 
338  ;  of  South  America,  405 

Mustela,  atrata,  56  ;  kenaiensis,  92  ; 
arcticus,  92 

Mutelidae,   168,   380 

Mycetes,  364 

Mylodon,  70,  153,  235 

Myocastor  coypus,  283,  396 

Myrmeocystus,  melliger,  216  ;  mexi- 
canus,  216 

Myomorphus    cubensis  (see    Megaloc- 


Myopotamus  (see  Myocastor}. 
Mysis,   distribution    and    origin,    48  ; 
relicta,  48  ;  oculata,  48 


N 

Nabis  capsiformis,  391 

NANSEN,  pre-glacial  elevation  of  land, 
14 

Nasua,  rufa,  249  ;  olivacea,  249 

NATHORST,  on  musk-ox,  7  ;  effects  of 
Glacial  Epoch  on  arctic  flora,  17 

Natrix  (see  Tropidonotus). 

"  NATURAL  SCIENCE,"  anonymous 
writer  on  origin  of  reindeer,  4 

Nebria  gyllenhali,  24 

Necrolestes,  246,  399,  404 

Necturus  maculatus,  136 

NEHRING,  relationship  of  Cerius  cana- 
densis,  68 

NELSON,  external  features  of  Green- 
land hare,  9 ;  distribution  of  rabbits, 
226  ;  Tres  Marias  islands,  330 


488 


INDEX 


Nelsonia,  201 

Nemorrhaedus,  83,  106 

Nenia  (see  Clausilia). 

Neocyclotus,  268 

Neofiber,  64,  182 

Neomylodon  (see  Grypotherium) . 

Neotomodon,  201 

Nephila,  clavipes,  190  ;   clavata,  191 

Nesodon,  399 

Nesolagus,  225 

Nesomimus,  301,  315 

Nesopelia,  301 

Nesoryzomys,  indefessus,  299  ;  ?wzr- 
boroughi,  299 

Nesospiza,  393 

Neuroptera  of  Florida,  178  ;  of  Cen- 
tral America,  258  ;  of  Antilles,  289 

Neii.rotrichus,  321  ;   0i&6*t,  201 

Newfoundland,  survival  of  fauna  from 
pre-glacial  times,  41  ;  geological 
history,  55  ;  fauna  of,  56 

Newportia,  350 

NEWTON,  Falkland  island  fossils,  430 

Nicaragua,  Lake,  fauna  of,  240 

Nicoletietta,  258 

Nome,  marine  gravels  at,  97 

Nonionina  depressula,  47 

North-Eastern  States,  reptiles,  123 — 
135  ;  amphibians,  135 — 139  ;  flora, 
139—141  ;  mammals,  141—143 

NORDENSXIOLD,  on  Mastodons,  408 

Notiodrilus,  412  ;  bovei,  431  ;  falc- 
landicus,  431 

Notiosorex,  201 

Notostylops,  400—402 

Notropis,  cornutos,  50  ;  atherinoides, 
50 

Nova  Scotia,  land-bird  fauna,  56 

Nycterinus,  215 

Nysius,  391 


Ocean  floor,  composition  of,  between 
America  and  Galapagos,  332 

Oceanodroma  cryptoleucura,  302 

Ochotona  collaris,  92 

Octodontidae,  371 

Odocoileus,  origin  of,  107—110,  396; 
hemionus,  107  ;  virginianus,  108, 
396  ;  columbianus,  108,  avius  109 


Odonata,  258 

Oeneis  semidea,  36,  38 

Oleacinae,  272 

"  Olm,"  136 

Oniscus  asellus,  39 

Oniticellus,  215 

Onychodectes,  244 

Onychomys,  201 

Onychophora,  345—347,  432 

tfpeas,  380,  385,  393 

Ophisaurus,  distribution  of,  281  ;  ven- 
tralis,  173,  221  ;  apus,  173,  221 

Opisthacanthus,  382 

Opisthopatus,  346,  432 

Opossum,  range,  182  ;  past  history, 
229  ;  in  West  Indies,  283  ;  in  South 
America,  366  ;  in  Santa  Cruz  beds, 
403 

OPPENHEIM,  on  Helicidae,  206 

Oreamnos,  origin  of,  106  ;  kennedyi, 
92  ;  montanus,  105 

Oreohelix,  206 

Oreotrochilus,  367 

Orestias,  361,  362 

Orthalicinae,  270,  273 

ORTMANN,  distribution  of  Cambarus, 
177  ;  distribution  of  freshwater 
crayfishes,  217 — 220;  Central  Ameri- 
can crabs,  239,  240  ;  freshwater 
crabs,  255  ;  land  -  bridge  between 
Mexico  and  Cuba,  291  ;  development 
of  Central  America  and  Antilles., 
292  ;  origin  of  Galapagos,  314  ; 
Miocene  marine  fauna  of  Peru,  334; 
geological  history  of  South  America, 
339,  340  ;  south  Atlantic  land- 
bridge,  381 — 383;  on  Ihering's  Arch- 
helenis,  382  ;  on  age  of  Santa  Cruz 
beds,  398  ;  Chilean  crayfishes,  405  ; 
on  Antarctic  continent,  419,  420,  424 

Orycteropidae,  373 

Orycteropus,  372 
Oryctolagus  cuniculus,  225 
Oryzomys,  range  of,  284  ;  metis,  284; 
antillarum,  284;  galapagoensis,  299; 
bauri,  299  ;  nelsoni,  299 
OSBORN,  connection  between  North  ,and 
and    South   America   in   Cretaceous 
times,  71,  227  ;  connection  between 
Asia  and  North  America,  84,  819  ; 
dispersal  of  camels,   86  ;    distribu- 


INDEX 


489 


tion  of  fossil  elephants,  87  ;  origin  of 
Cervidae,  110  ;  middle  Miocene 
fauna,  112  ;  fossil-beds  of  western 
America,  119,  120  ;  faunal  phases 
in  North  America,  120—122  ;  cause 
of  extinction  of  species,  146  ;  Oligo- 
cene  horses,  147  ;  Lower  Pleistocene 
mammals,  153  ;  mammal  horizons, 
correlation  of,  226,  227  ;  Eocene 
affinities  between  Europe  and  North 
America,  228  ;  Oligocene  affinities 
between  Europe  and  America,  229, 
230,  294,  357  ;  on  Miocene  and'  Plio- 
cene faunas,  230,  231  ;  prigin  of 
Central  America,  243  ;  armadillo  in 
Eocene  beds  of  North  America,  244; 
dispersal  of  manatees,  279  ;  geo- 
logical evolution  of  South  America, 
341,  342  ;  origin  of  North  Ameri- 
can bears,  351  ;  tapirs  in  North 
America,  352,  353  ;  Miocene  eden- 
tates in  North  America,  358,  402, 
409  ;  Miocene  sea  in  Amazon  valley, 
360  ;  Eocene  deposits  in  Patagonia, 
367  ;  on  absence  of  land-connection 
between  South  America  and  Old 
World,  371  ;  ancestors'  of  camels, 
407  ;  Antarctic  continent,  419 

OSGOOD,  reindeer  in  Alaska,  5  ;  on 
Scaphoceros,  155 

Ostriches,  present  and  former  range, 
373,  374 

Otocryptops,  382 

Otostomus  (see  Drymaeus). 

Otter,  in  Newfoundland,  56  ;  in  Pleis- 
tocene deposits,  153 

Ovibos,  distribution,  6 — 9,  86  ;  an- 
cestry, 154,  155  ;  moschatus  mac- 
kenzianus,  59 

Oms,  nivicola,  85,  86,  105  ;  borealis, 
86  ;  canadensis,  104  ;  scaphoceras, 
105  ;  cavifrons,  155 

Oxystyla  undata,  176 

Oxytelus,  391 


Pacific  continent,  evidence  for  the 
former  existence  of,  321 — 328  ;  pro- 
bable subsidence  before  Tertiary 
Era,  328 


Pacific  land-belt,  theory  of,  409,  410, 
427 — 429  ;  southern  faunistic  affi- 
nities explained,  426 

Pacific  islands,  geological  formation 
of,  322,  326 

PACKARD,  Labrador  fauna  and  flora, 
27;  subterranean  faunas,  165;  South 
Atlantic  land-bridge,  381 

Paddle-fish  in  Mississippi,  88,  89 

PAGENSTECHER,  affinities  of  Greenland 
lepidoptera,  22  ;  lepidoptera  of 
Kocky  Mountains  and  Europe,  117  ; 
butterflies  of  Florida,  179  ;  Cali- 
fornian  butterflies  and  moths,  214  ; 
on  Antillean  lepidoptera,  289 

Palaemonetes,  291 

Palaeolagus,  226 

Palaeolama,  406 

Palaeomastodon,  358 

Palaeomeryx,  112 

Palpigrada,  217 

Panama,  isthmus  of,  geology  of,  236, 
237  ;  date  of  submergence  of,  238; 
sunken  land  westward  of,  331 

Pangolin,  372 

Panolopus,  281  i 

Panopeus  bermudensis,  333 

Paramylodon,  153 

Parascalops  breweri,  142 

Parastacidae,  420,  424,  426,   432 

Parastacus,  405 

Pardosa  groenlandica,  36 

ParTiassius,  range  of  genus,  90,  91  ; 
nomion,  90  ;  sminthus,  90  ;  thor, 
90  ;  clodius,  90  ;  clarius,  90 

Paroscya   bermudensis,   189 

Parrot,  Florida,  159,  172  ;  in  Central 
America,  250  ;  showing  affinity  be- 
tween Africa  and  America,  373 

Parus,  56 

Patagonia,  fossil  fauna  of,  398—404  ; 
land-connection  with  western  North 
America,  402  ;  affinities  to  south 
Africa,  Australia,  and  New  Zealand, 
405 — 416 

Patula,  solitaria,  72  ;  strlatella,  72 

PAULCKE,  cretaceous  deposits  in  South 
America,  359 

PAULMIER  (see  ECKEL). 

Peccary  in  North  America,  153,  156 

Pectinator,  372 


490 


INDEX 


Pedetidae,  372,  373 

Pellegrinia,  372 

Pelobates,  204  ;  syriacus,  221 

Pelobatidae,  204,  221 

Pelodytes,  221 

PENHALLOW,  Pleistocene  flora  of 
Canada,  43,  44 

Pentalagus,  225 

Peratherium,  367 

Perch,  absent  from  western  States,  198 

Percidae,  198 

Peripatus,  range  and  origin  of,  345 — 
347,  362,  432  ;  eiseni,  346  ;  goudoti, 
346  ;  tholloni,  369 

Permanence  of  ocean  basins  theory, 
214—232,  272—281,  321—333 

Perodipus,  201 

Peromyscus,  maniculatus,  27  ;  sit- 
kensis,  92 

Peru,  geological  history  of,  359  ; 
poverty  of  freshwater  fauna,  405 

PESCHEL,  meaning  of  term  "relict 
lake,"  49 

PETERSEN,  Polar  centre  of  distribu- 
tion for  butterflies  and  moths,  22 

Petromys,  372 

Pezzotettix,  glacialis,  36;  borealis,  36; 
frigida,  36 

PFEFFER,  sub-universal  distribution  of 
species,  374,  375  ;  distribution  of 
Lepidosirenidae,  378 

Phaeolaema,  350 

Phasmidae,  158 

Philomycus,   412 

Philonthus,  391 

Philoscia,  bermudensls,  190  ;  couchi, 
190 

Philyra  pisum,  93 

Phlaocyon,  151,  152 

Phoca,  280 

Phragmatobia  Juliginosa,  214 

Phrynosoma,  127,  202 

Phyllodactylus  tuberculosus,  304 

Pica,  rustica,  87  ;  nutalli,  88 

PICKARD-CAMBRIDGE,  Central  Ameri- 
can spiders,  258  ;  spiders  of  St. 
Helena,  388,  389 

Pigidium  rivulatum,  361 

Pike,  as  evidence  of  old  land-connec- 
tion of  America  with  Asia,  83  ; 
"  bony,"  89  ;  in  Mississippi,  163,  164 


PILSBRY,  mollusks  of  Florida,  175, 
176  ;  mollusks  of  Bermuda,  191— 
193  ;  on  eastern  and  western  faunal 
provinces,  198  ;  family  Helicidae, 
205,  206,  212  ;  on  Arionidae,  212, 
213  ;  on  Urocoptidae,  267,  268  ; 
geological  history  of  Antilles,  267  ; 
on  groups  of  Bulimulus,  270,  307  ; 
on  Pacific  continent,  322,  323  ;  dis- 
tribution of  Achatinidae,  380  ;  mol- 
lusca  of  St.  Helena,  390  ;  Chilo- 
nopsis,  390  ;  convergence  among 
Bulimuli,  410  ;  Helicigona  and 
Arianta,  411 

"  Pine-barren  "  flora,  140,  141 

Pinicola,   56 

Pipa  americana,  377 

PIRIE,  sedimentary  rocks  in  South 
Orkneys,  433 

Pitymys,  range  implying  great  anti- 
quity, 223,  224  ;  incertus,  223  ; 
quasitor,  224  ;  pinetorum,  224  ; 
nemoralis,  224 

Placostylus,  209,  307 

Plagiodontia,  282,  283 

Plagiola,  254 

Planorbis,  nathorsti,  21  ;  arcticus,  21  ; 
noronhensis,  385 

Plants,  as  tests  of  climate,  43,  175  ; 
in  Pleistocene  beds,  44  ;  of  Rocky 
Mountains,  114  ;  common  to  eastern 
States,  Japan  and  Himalayas,  139  ; 
affinity  in  mid-Cretaceous  times  be- 
tween Argentina  and  Dakota,  414  ; 
common  to  Eocky  Mountains,  and 
southern  South  America,  415 

Platatherium,  113 

Platygonus,  153 

Plectocyclotus,  268 

Plekocheilus,  aurissileni,  269  ;  aula- 
costylus,  269 

Plestiodon,  123 

Plethodon,  412  ;  cinereus,  31 

Pleurodonte,  272 

Pliauchenia,  153,  407 

Plover  of  St.  Helena,  387 

Plutonium,  350 

POCOCK,  myriopods  of  Bermuda,  189  ; 
distribution  of  scorpions,  382  ;  on 
affinity  between  western  North 
America  and  Argentina,  412 


INDEX 


491 


Podocnemis,  distribution  of,  374,  375  ; 

expansa,  360 
Poeciliidae,  166 
Poecilozonites,  192,  193 
Polar  origin  of  life,  23,  24,  427,  428 
Polygyra,  198,  205  ;  monodon,  31 
Polyodon  spathula,  88 
Pomadasis    grandis,   241 
Powboporeia,  hoyi,  49  ;  filicornis,  49 
POPPIUS,  distribution  of  arctic  Coleop- 

tera,  21 

Porcellio  parmcornis,  190 
Porcupine,    Canadian,    27,    69,    431  ; 

South  American,   366,  403 
Porites,  239 
Porphyriornis,  393 
Port  Kennedy  cave  fauna,  153 
Potamoblidae,  218—220,  426 
Potamobius,  218—220 
Potamocarclninae,  381 
Potamoninae,  255,  381 
Potos,  249  (See  also  Cercoleptes.) 
Potter  Creek  cave  fauna,  61,  153 
Prairie-dog,    148 
"  Prairie-plains,"  144 
Prairie-wolf,  148 
Praticolella,  175 
PREBLE,  distribution  of  Zapus,  29  ;  on 

Hudson  Bay  region,  31  ;   report  on 

Athabasca-Mackenzie  region,   58 
Prenolepis    kincaidi,    189 
Primates  in  North  American  Eocene 

beds,  228,  230 
Proboscidea,  230 
Procapromys  geayi,  283 
Procellariidae,  302 
Procyon,  lotor,  151  ;  simus,  152;  may- 

nardi,  181,  249 

Procyonidae,  151,  152,  181,  249 
Prolagostomus,  403 
Prong-horn,    range    and   ancestry   of, 

112,  113 

Prophysaon,  212 
Prorastomus  veronensis,  280 
Proscalops,  143 
Protauchenia,  406 
Proteidae,  136 
Proteocordylus,  135 
Proteodidelphys,  367,  403 
Proteus  anguineus,  136 
Protopterus,  378  ;    libycus,  379 


Protracheata  (see  Onychophora). 
Protylopus,  407 
Psephurus  gladlus,  89 
Pseudobranchus  lateralis,  172,  173 
Pseudoneuroptera  of  Antilles,  289 
Pseudothelphusa,   255,   362  ;      colom- 

biana,     256  ;       americana,      291   ; 

terrestris,  291  ;   affinis,  291 
Pseudopus,  380 
Psittacidae,  373 
Psittacotherium,  244 
Ptarmigan,  willow,  62  ;    rock,  62 
Pterosphenus,  278 
Pudu,  354  ;  in  Chile,  418 
Pudua  mephistopheles,  354 
Puma,  106,  107 
Pwpa  in  Galapagos  islands,  306,  308  ; 

in     Fernando     de    Noronha,     385  ; 

hoppei,  21  ;     muscorum,  72  ;    armi- 

fera,  72  ;  holzingeri,  72 
PUTNAM,    fauna    of    Mammoth    Cave, 

164,  165 

Putorius,  pygmaeus,  85  ;   rixosus,  85 
Pyrameis,  atalanta,  214  ;     cardui,  214 
Pyrotheria,  400 


QUACKENBUSH,   mammoth   remains  in 

Alaska,  80 
Quesal,  250 

R 

Rabbits,  affinities  and  ancestry  of,  225, 

226 

Raccoon,  151,  181,  249,  283 
Raccoon-fox,  201 
Eana,    pipiens,    31  ;     palustris,     31  ; 

cantabrigiensiSf  31  ;    septentrionalis, 

31 

RANGE,  DE  (see  FEILDEN). 
Rangifer,  tarandus,  3  ;    spitsbergensis, 

3  ;    caribou,  3  ;    stonei,  5  ;    osborni, 

5  ;   montanus,  5,  92  ;    terrae  novae, 

56  ;    arcticus,  59 

Rat  on  Galapagos  islands,  298,  299 
RATHBUN,     distribution     of      Pacific 

Crustacea,      93,      94  ;        freshwater 

crabs    of    Central    America,    255  ; 

crabs  of  Peru,  333 


492 


INDEX 


Ked-deer,  origin  of,  68 

Red-fin  in  drift  area,  50 

REGAN,  on  bony-pikes,   164  ;     Central 

American  Cichlidae,  234  ;    land-con- 
nection between  South  America  and 

Africa,  379 

Regulus,  in  Nova   Scotia,   56  ;      dis- 
persal,    114,    115  ;     cuvieri,    115  ; 

satrapa,  115  ;     calendula,  115 
REHN  and  HEBAED,  Bermudan  Orthop- 

tera,   189  ;    Orthoptera  of   Florida, 

179 
Reindeer,   forms   of,    3,   4  ;     original 

home,    4,    5  ;     extinct    Irish,    12  ; 

in   Iceland,    12  ;     former  range   in 

Europe   and   America,    6,    35  ;      in 

Newfoundland,  55 
Reithrodon,  431 

Relict  lakes,  explanation  of  term,  49 
Rhamphastidae,  250,  368 
Rhea,  373,  374,  396 
Rhinema  floridana,  173 
Rhineura,  203 
RMnocerotidae,   229 
RHOADS,   structure  of  Greenland  hare, 

9 

Rhopalomesites,  178 
Rhynchophora,  387 
Rhynchopsittacus,   172  . 
Rhysida,  382 

RICE,  geology  of  Bermuda,  184 
Rice-rats,  in  Antilles,   284,   285  ;     in 

Galapagos,  298 
RICHAEDSON,  isopods  of  Florida,  179  ; 

isopods  of  Bermuda,   190 
RIDQWAY,  birds  of  Galapagos,  301 
RIDLEY,  on  Fernando  de  Noronha,  384, 

385 

RIFFABTH   (see  STICHEL). 
ROBBINS  and  COCKERELL,   on    Veroni- 

cella,  194 
ROBINSON  and    GREENMAN,    flora    of 

Galapagos  islands,  314,  315 
Rockall  Bank,  shallow  water  species 

dredged  near,  17 
Rocky   Mountains,    100 — 104  ;    plants 

of  in  Southern  Andes,  414—418 
Roe-deer,  affinity  with  American  deer, 

111 

Romerolagus,  226 
Roma,  affinity  of  American  deer,  111 


ROTH,  fauna  of  Santa  Cruz  beds,  399, 
400 

ROTHSCHILD  and  HAETEET,  birds  of 
Galapagos  islands,  302 

ROOSEVELT,  land  reserves  in  Rocky 
Mountains,  118,  119 

Rumina  decollata,  192,  273 

Rupicapra,  106 

Rupicola  crocea,  362 

Ruscinomys,  372 

RUSSELL,  extent  of  American  ice-sheet, 
33  ;  former  drainage  of  Mississippi, 
54  ;  description  of  Rocky  Moun- 
tains, 102  ;  absence  of  trees  in 
prairies,  145 

RUTHVEN,  prairie  forms  of  animal 
life,  145  ;  origin  and  varieties  of 
garter-snakes,  128,  222 

RUTIMEYER,  on  Antarctic  continent, 
420 

RYDBERG,  antiquity  of  Rocky  Moun- 
tain flora,  103 

S 

Salamander,  giant,   135,   136  ;     tiger, 

136,  137  ;    blunt-nosed,  136 
Salamandridae,  136,  137 
Salda,  391 

SALISBURY  (see  CHAMBERLIN). 
SALVIN  and  GODMAN,  birds  of  Central 

America,   250  ;     insects   of   Central 

America,  258 
SALVIN,   birds   of    Galapagos   islands, 

301 
SANDBERGER,    on    Tertiary    mollusks, 

176  ;    on  Helicidae,  206 
Santa  Cruz  fossil  beds,  246,  398—404 
SAEASIN,  on  age  of  Coeciliidae,  251  ; 

on  age  of  Typhlopidae,  252,  288  ; 

origin  of  Galapagos,  313  ;    dispersal 

of  Herpele,  370 
Saturnidae,  381 
Sauresia,  281 
Scalaria  rugulosa,  428 
Scalops  aquations,  142 
Scapanus,  201 

Scaphiopus,  204,  220  ;    holbrooki,  205 
Scaphirhynchus,   83  ;     platyrhynchus, 

88 

Scaphoceros  tyrelli,  155 
Scarabaeidae,  425 


INDEX 


493 


Sceloporus  undulatus,  123,  126,  127 

Schistomys,  403 

SCHLOSSER,  origin  of  reindeer,  4  ;  on 
value  of  zoogeographical  evidence, 
120,  223  ;  geological  age  of  Vis- 
caciidae,  354 

SCHMIDT,  fish  fauna  of  northern  Sea 
of  Japan,  94 

SCHUCHERT,  palaeogeography  of  Cali- 
fornia, 198  ;  palaeogeography  of 
North  America,  228—231  ;  on  Cen- 
tral America,  237,  238  ;  antiquity 
of  Bahamas,  264,  293 

SCHWARZ,  Col&optera  of  Florida,  178 
geology  of  Ascension,  384 

Scincidae,  123,  124,  189,  376 

Sciuropterus,  sabrinus,  63,  64  ;  yukon- 
ensis,  63,  92 

SCLATER,  W.  L.,  and  P.  L.  SCLATER, 
distribution  of  seals,  280 

Scoliopterix  libatrix,  214 

Scolopendra  morsitans,  382,  386 

Scolopendridae,  382 

Scorpions  in  Florida,  178  ;  of  western 
America,  349,  350  ;  of  St.  Helena, 
389 

SCOTT,  on  Cervalces,  32  ;  Steiromys  an 
ancestor  of  Erethizon,  71  \Necro- 
lestes,  246,  404  ;  on  Santa  Cruz 
fauna,  398 — 404  ;  origin  of  eden- 
tates, 401  ;  Antarctic  continent, 
422 

Seals,  distribution  of,  280  ;  "  ele- 
phant," 428 

Sea-urchins,  fossil,  of  West  Indian  and 
Mediterranean  areas,  278 

SEDGWICK,  distribution  of  Onycho- 
phora,  346 

Semotilus  corporalis,  51 

SETON,  mountain  caribou,  5,  6  ;  range 
of  moose,  32  ;  range  of  wapiti,  67 

SEWARD,  fossil  plants  as  tests  of  cli- 
mate, 43 

SHALER,  effect  of  warm  current  on 
Polar  regions,  99  ;  former  eleva- 
tion of  Florida,  169 

SHARPE,  birds  of  Bermuda,  188,  189 

Sheep,  range  of  in  America,  6  ;  ex- 
tinct, in  Alaska,  80  ;  in  English 
Forest  Bed,  85  ;  in  Nicaragua,  105 

SHIMEK,  on  Helicina,  158 


Sialls  bermudianus,  188 

Siberia,  fauna  of,  in  Glacial  times,  82 

SIEBENROCK,  distribution  of  turtles, 
132 

Siluridae,  380 

SIMPSON,  distribution  of  Unlonidae, 
52,  54  ;  sub-divisions  of  Unionidae, 
254  ;  geological  history  of  Florida, 
177  ;  Antillean  molluscan  fauna,  265 
—267 

Simpulopsis,  270 

SIMROTH,  on  Arionidae,  213  ;  mode 
of  dispersal  of  AmdLia,  214  ;  origin 
of  Bulimulidae,  273  ;  pendulation 
theory,  434 

SINCLAIR,  discovery  of  Euceratherium, 
154  ;  Santa  Cruz  fossil  beds,  403, 
404  ;  Miocene  beds  in  Oregon,  408, 
409 

Siren  lacertina,  173 

Sistrurus,  131 

Sitta,  56 

Skinks,  123,  189,  376 

Skunks,  western,  201 

Sloth,  in  Brazil,  365,  366  ;  ground, 
244,;  giant  ground,  in  North 
America,  153,  156  ;  in  South 
America,  400  ;  gravigrade,  re- 
mains in  Oregon,  408 

SMITH,  Edgar  A.,  mollusca  of  St. 
Helena,  389,  390 

SMITH,  Eugene  A.,  elevation  of 
Florida,  170 

SMITH,  G.,  My  sis  relicta  in  Lake 
Superior,  48 

SMITH,  Geoffrey,  faunistic  affinity  of 
Tasmania  and  South  America,  424 

SMITH,  J.  P.,  similarity  of  marine 
faunas  of  Japan  and  America,  96  ; 
geology  of  California,  199,  356,  357  ; 
northern  marine  faunas,  318 

Snakes  in  eastern  North  America, 
127  ;  garter,  127,  128,  222  ;  rough 
green,  130,  197  ;  smooth  green,  130 
197  ;  rattle,  131,  253,  352  ; 
burrowing,  252,  253  ;  glass,  173, 
221,  281  ;  blind,  203 

SNODGRASS  and  HELLER,  birds  of  Gala- 
pagos, 302 

Solenodon,  paradoxus,  282  ;  cubanus, 
282 


494 


INDEX 


Solenodontidae,  282 

SOLLAS,  coral-boring  at  Funafuti,  321 

"  Sonoran  "  region,  196 

Sonorella,  206 

Sorex,  tundrensis,  92  ;  glacialis, 
92  ;  pribilofensis,  92 

South  America,  northern  animals  in, 
235  ;  climate  and  fauna,  336,  337  ; 
past  geography,  338—345,  359,  360  ; 
faunistic  affinities  of,  344 — 350  ; 
affinity  with  European  Tertiary 
fauna,  355  ;  relationship  with 
Madagascar,  375  ;  affinity  with 
Africa,  368—383 

South  Orkney  islands,  433 

South  -  Western  States,  196  ;  as 
original  home  of  eastern  forms, 
197  ;  gradual  desiccation  of,  200 — 
204  ;  affinity  with  Europe,  205—231. 

Sparassodonta,  373 

SPEIGHT,  geology  of  mid  -  Pacific 
islands,  327 

Spelerpes,  age  of  genus,  172,  221,  246; 
in  Antilles,  281  ;  in  South  America, 
347;  orizabensis,137;  leprosus,  137; 
chiropterus,  137  ;  fuscus,  138,  221; 
infuscatus,  281 

SPENCER,  pre-Glacial  elevation  of  land, 
14,  15  ;  drainage  of  Great  Lakes 
in  pre-Glacial  times,  54  ;  elevation 
and  submergence  of  Florida,  169, 
170  ;  Cuban  cave  fossils,  285  ;  West 
Indian  land-bridge,  286  ;  Antillean 
continent,  293 

Spermophilus  (see  Citellus). 

SPETHMANN,  land-bridge  between 
Europe  and  Greenland,  18 

Sphaeroniscus,  190 

Spherilloninae,  320 

Sphingidae,  117 

Spider,  silk,  in  Bermuda,  190,  191; 
spiders  of  Central  America,  258  ; 
of  St.  Helena,  388,  389 

Spinus,  56 

STANDFUSS,  affinities  of  Vanessa,  91 

STAPF,  arctic  grasses  found  in  Argen- 
tina, 416 

Staten  island,  429 

STEARNS,  on  Galapagos  islands,  291  ; 
accidental  dispersal,  300,  306  ;  mol- 
lusca  of  Galapagos,  305 


STEBBING,  on  Cambaroides,  218 

Steiromys,  71,  403 

STEJNEGER,  on  origin  of  reindeer,  5  ; 
range  of  ptarmigan,  62  ;  land- 
bridge  between  Asia  and  North 
America,  83  ;  distribution  of  Cin- 
clus,  113  ;  distribution  of  ground- 
lizard,  124  ;  on  Tropidonotus,  129  ; 
discoglossoid  toads,  204  ;  Antillean 
reptiles  and  amphibia,  288 

Stenamma  westwoodi,  215 

Stenogyridae,  192 

STEWART,  botany  of  Galapagos,  315, 
316 

St.  Helena,  fauna,  affinities  of,  386 — 
391  ;  flora,  391,  392 

STICHEL  and  EIFFARTH,  on  Heli- 
coniidae,  368 

Stilauchenia,   406 

STIMPSON,  My  sis  relicta  in  Lake 
Michigan,  48 

STOLL,  mites  of  Guatemala,  257,  258 

Stomion,  413 

STRAND,  distribution  of  arctic  spiders, 
21 

STREBEL,  on  Orthalicinae,  270 

Streptaxidae,   348 

Strobilops  labyrinthica,  31 

Strobilus,  272 

Strophocheilus ,   362 

Struthio,  374 

Sturgeon,  shovel-nosed,  88 

Stygicola  dentatus,   290 

Subulina,  272,  380 

Succinea,  in  Galapagos,  306,  308  ;  in 
St.  Helena,  390  ;  groenlandica,  21, 
24  ;  bermudensis,  192,  193  ;  barba- 
densis,  192 

"  Suckers,"  89 

SUESS,  ancient  land  "  Laurentia,"  26  ; 
absence  of  land-connection  with 
Asia  in  Pliocene  times,  84  ;  great 
Pliocene  subsidence  of  land,  195  ; 
Cape  Kegion  of  California,  199  ; 
north  Atlantic  land-bridge,  229, 
231  ;  distinctness  of  Central 
America  from  North  and  South,  237, 
261  ;  Antillean  mountain  system, 
263  ;  permanence  of  ocean  basins, 
276,  387  ;  Galapagos  islands  a  con- 
tinuation of  American  mountain 


INDEX 


495 


chain,   297  ;    ancient  western  rocks 

in   South  America,  345  ;     elevation 

of  Lake  Titicaca,   361 
"  Swift  "  lizard,  123,  126,  127 
Sylvilagus,   225 
Symbos,  153—155  ;   tyrelli,  80 
Symbranchus     marmoratus ,   290 
Synaptomys,    innuitus,    27  ;      sphag- 

nicola,  37  ;  cooperi,  28  ;    wrangeli, 

92  ;  dalli,  92 
Systemodon,  228,  353 
Systrophia,  348 


Talpa  europaea,  142 

Talpidae,  142,  143 

Tamias  caniceps,  92 

Tapiridae,  228,  352,   353 

Tapirus,  americanus,  352  ;  haysi,  352  ; 
arvernensis,  353 

Tarantulldae,  382 

Tayassus  tetragonus,  156 

TCHERSKI,  wapiti  deer  and  Siberian 
maral,  68  ;  conditions  of  climate  in 
Siberia  in  Glacial  Epoch,  82  ;  fossil 
mammals  in  Siberia,  86  * 

Teanopus,  201 

Tehuantepec,  isthmus  of,  236 

Teiidae,  369 

Tenebrionidae,  215,  413 

Tennessee  river,  alteration  of  its 
course  illustrated  by  distribution  of 
shells,  62 

Teonoma  saxamans,  92 

Terrap&ne  putnami,  134 

Terrapin,   132 

Testudo,  315 

T etrabelodon,   231 

Thamnophis,  128,  222  ;     sirtalis,    127 

Theatops  erythrocephalus,  217 

Theridomyidae,  354 

THOMAS,  on  meadow-voles,  224  ;  dis- 
covery of  Caenolestes,  350 

Thryonomys  swinderianus,  372 

Thylacinidae,  399,  403 

Thylacinus,  399 

Thynnidae,  433 

Thysanophora  hypolepta,  192,   193 


Thysanura,  411,  412 

Tierra  del  Fuego,  faunistic  affinity  of, 

429—431 
Tillodontia,  244 
Titicaca,  Lake,  361 
Tiger,  sabre-tooth,  153,  200 
Tityus  floridanus,  178 
Toads,  in  south-western  States,  204  ; 

spade-foot,    205,    220  ;      tongueless, 

377  ;    Surinam,  377 
Todies,  289 
Toditae,  289 

TOLL,  fossil  mammals  in   Siberia,   82 
Tomigerus,  389,  390 
Tomocyclus,  269 

Tornatellina,  306  ;     chathamensis,  308 
Tortoises,  land  and  freshwater,  in  drift 

area,  51  ;    geological  history  of,  132, 

222,  236  ;    in  Central  America,  251  ; 

of  Galapagos  islands,  302,  303,  312, 

313  ;     of   Africa,    Madagascar,   and 

South  America,  374 
Toucans,  250,  368 
TOULA.  Tertiary  fauna  of  Gatun,  238  ; 

Tertiary  fauna  of  Panama,  243 
Toxodontia,  399 

TRANSEAU,   bog    plant   societies,    34 
Tree-frog,  Florida,  173 
Tree-swifts,  368 
Tremarctos   ornatus,  350,   351 
Trematherium,  366 
Tres  Marias  islands,  330 
Tribolonotus,  126 
TrichechiLS,   mwnatus,   279  ;    inunguis, 

279,  360  ;  senegalemis,  279 
Trichodina,  390 
Trichoniscidae,  190 
Triglopsis  thompsoni,  49 
Trilophodon,  259 
Trinidad  island,  flora,  385,  386 
Tristan   da   Cunha,    flora   and   fauna, 

393 

Tristania,  393 

TRISTRAM,  polar  origin  of  life,  23,  24 
Trochilidae,  250,  367 
Trogon,    resplendens,   250  ;     gallicus, 

250 

Trogonidae,  geological  history  of,  250 
Tropidonotus,  range  and  age  of,  128, 

129,  222  ;    validus,  222  ;   viperinus, 

222 


496 


INDEX 


Tropidurus,  304,  315 

TROTTEK,  origin  of  land-bird  fauna  of 

Nova  Scotia,  56 
Truncatella,  176 
Tudorella,  272 
TOLLBERG,  dispersal  of  Microtus,  28  ; 

origin    of    meadow-voles,    223  ;    on 

South    Atlantic    land-bridge,     372, 

373,  405 

Tundral  fauna  and  flora,  35 
Turkey,  in  North  America,  159 
Turritella,   ambulacrum,  428  ;     pata- 

gonica,  428 
Turtle,  spotted,  132  ;     diamond-back, 

132  ;     semi-box,    132  ;     box,    134  ; 

snapping,   134  ;    alligator  snapping, 

135 
Tylos,  latreilli,  179,  190  ;    niveus,  179, 

190 

Typhlichthys  subterraneus,  165 
Typhlomolge  rathbuni,  136 
Typhlopidae,  252,  253 
Typhtops,   tennis,  253  ;      lumbricalis, 

288 


ULBRICH,  distribution  of  Anemone,  114 

Umbra,  limi,  51  ;  krameri,  51 

Umbridae,   51 

Unio  luteolus,  162 

Unionidae,  distribution  of,  161,  198, 
254,  405  ;  on  Pacific  slope  of  North 
America,  162  ;  groups  of,  254  ;  on 
west  of  Andes,  338  ;  of  Chile  and 
New  Zealand,  420 

UPHAM,  elevation  of  north  -  eastern 
North  America,  41  ;  elevation  of 
Lake  Eegion,  54,  55 

Urania  leilus,  117 

Urochroa,  350 

Urocoptidae,   176,  206,  266 

Uropoda,  258 

Uropodias  bermudensis,  190 

Urotrichus,  321 

Ursidae,  350 

Ursus,  americanus,  28  ;  richardsoni, 
61  ;  middendorffi,  92  ;  kidderi, 
92  ;  daUi,  92  ;  eulophus,  92  ; 


kenaiensis,     92  ;       emmonsi,     92  ; 

malayanus,     352  ;       boeckhi,     352  ; 

etruscus,  352 
Uta,  127 
Utah,  lakes  of,  103 

, 


VALLENTIN,  Falkland  islands,  430 
VANATTA,  Bermudan  freshwater  shells, 

194  ;     on   Arionidae,  212 
Vanessa,  distribution  of,  91  ;     cardui, 

117  ;     antiopa,   214 
VANHOFFEN,  survival  of  life  in  Green- 
land during  Glacial  Epoch,   19 
Varicella,  175 

VAUGHAN,  geology  of  Florida,   171 
Venericardia  splanicosta,    199,    357 
Vernonia,  391 
Veronicella,  in  southern  Florida,  176  ; 

schivelyae,  192,  194  ;  moreletl,  194 
VERRILL,     Mysis     relicta     in     Lake 

Superior,  48  ;    geology  of  Bermuda, 

184,    185  ;     Bermudan   flora,     187  ; 

Bermudan    spider,     190  ;      Central 

American  corals,  239 
Vertigo,  ovata,  72  ;     ventricosa,  72 
Vireo,    bermudianus,   188  ;    novebora- 

censis,  188 
Viscacha,  353,  403 
Viscaciidae,  353,  403 
Vitrea,  306,  308 

Vitrina,   angelicae,   21  ;     limpida,   72 
Voles,  range  of,  28  ;     meadow,     223, 

224  ;   Jalapa  meadow,  224 
Vulpes,   lagopus,    11  ;     deletrix,   56  ; 

kenaiensis,  92  ;     pribilofensis,    92  ; 

beringensis,  92 


W 


WALKER,  distribution  of  Margaritana, 
51  ;  North  American  mollusca,  73  ; 
mollusca  of  Florida,  177 

WALLACE,  age  of  fauna  and  flora  of 
New  Zealand,  125  ;  age  of 
Australian  fauna,  150  ;  Falkland 
island  wolf,  151  ;  Bermudan  fauna 


INDEX 


497 


due  to  accidental  dispersal,  183,  184, 
188,  189  ;  Central  American  fauna, 
233,  234  ;  appearance  of  southern 
forms  in  North  America,  234  ; 
northern  element  in  South  America, 
235,  236,  259,  413  ;  Antillean  fauna, 
261  ;  Galapagos  islands,  296,  298, 
309  ;  permanence  of  ocean  basins, 
274 — 277  ;  faunal  characteristics  of 
South  America,  336,  337  ;  antiquity 
of  continent  of  South  America,  368  ; 
St.  Helena  an  oceanic  island,  386, 
387  ;  fauna  and  flora  of  St.  Helena, 
388,  391,  392 

WALTHER,  on  Pacific  coast  lines,  328 

Wapiti  deer,  distribution  and  origin, 
67—69 

Water-vole  of  Florida,  182 

WATSON,  flora  of  Calif ornian  islands. 
417 

Weasel,  85 

WEBER,  origin  of  Australian  dog,  151 

WEBSTER,  dispersal  of  butterflies  and 
moths,  116 

West  Indies  (see  Antilles). 

WHEELER,  Bermudan  ants,  189  ; 
honey-ants,  216  ;  Liometopum,  216 

WHITE,  C.  A.,  on  American  Unionidae, 
161 

WHITE,  P.  B.,  Remitter  a  of  St. 
Helena,  388,  390 

WHITE,  I.  C.  on  geology  of  Argentina, 
397 

White  Mountains,  fauna  and  flora,  35 
— 37  ;  relationship  with  Labrador 
and  Greenland,  42  ;  with  Kocky 
Mountain  flora,  103 

WHITFIELD  on  fossil  Unionidae,  161 

WHITNEY,  temperate  climate  in  Glacial 
Epoch,  19,  45,  46  ;  climatic  con- 
ditions necessary  to  a  Glacial  Epoch, 
75,  76  ;  glaciation  of  Kocky  Moun- 
tains, 102 

WILSER,  Polar  continent  as  origin  of 
life,  23 

WINGE,  on  arctic  hares,   9 

WINKLEY,  distribution  of  Helix 
horten&is,  14 

WOLF,  Galapagos  islands,  296  ;  flora 
of  Galapagos,  309,  310 


Wolf,  arctic,  11  ;  barren-ground,  61  ; 
in  Alaska,  61  ;  Falkland  island,  150, 
430,  431  ;  in  South  America,  396  ; 
Tasmanian,  399,  403 

WOLLASTON,  beetles  of  St.  Helena, 
387 

Wolverine,    61 

Wood-chuck,  63 

Wood-lice,  179,  190,  309 

Wood-rats,   201 

WOODWARD,  A.  S.,  Grypotherium 
listai,  401  ;  Miolania,  404  ;  on  Pro- 
rastomus,  280  ;  on  Bradytherium, 
366.  (See  also  MORENO.) 

WOODWARD,  B.  B.,  distribution  of 
marine  mollusks,  16  (See  also  KEN- 
NARD.) 

WOODWARD,  S.  P.,  on  Atlantic  land- 
bridge,  272 

Worm-lizard,  173 

WORTMAN,  North  American  origin  of 
Ganodonta,  244  ;  origin  of  eden- 
tates, 401 

Wren,  golden-crested,   114 

WRIGHT,  J.,  Foraminifera  in  boulder 
clay,  47 

WRIGHT,  G.  F.,  and  UPHAM,  survival 
in  Greenland  of  musk-ox,  8  ;  eleva- 
tion of  northern  lands  in  Pliocene 
times,  15 

Wyoming,  game  preserve  in,  119 


Xantholinus,  391 
Xenomys,  201 
Xenopus,  377 
Xenotherium,  246,  404 


Tagansia,  431 
Yellowstone  Park,  118 


Zapus,  hudsonius,  27,  29  ;  setchuanus* 

29 

Zonitoides  nitidus,  72 
Zophobas  morio,  390 


BRADBURY,  AONEW   &   CO.   LD.,   PRINTERS,    LONDON  AND  TONBRIDGK. 


L.A. 


KK 


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